Hi there!
I am, same as you, living in a rental, and have been for most of my life.
You don't feel limited once you learn the alternatives. For example, in the city I live in, drilling into the walls more than like...2 holes per wall is not allowed to the tenant. If you do you must pay a fine, AND re-paint any wall they ask you to once you leave the lease. There are many more very strict rules here, so it is tough here being an artist and renting a house!
Having a small room, I wanted, at first, everything on the walls; wall easels, shelving and hanging, to save me space in the middle of the room. Of course I can't with these strict rules! I am actually JUST setting up my studio right now! We just moved here a few days ago!
Here's some of what I am doing:
To get my storage for art supplies, I have enlisted the local Goodwill for bookcases. I measured the wall I can dedicate to storage, and I want to use it floor to ceiling as I don't have much space in here.
I'll be buying 4 bookcases, 2 large ones and 2 smaller ones. I will drill the smaller bookcases into the top of the large ones, and fasten the top of each double bookcase, to the wall for extra support. Now I only have 2 screws in the wall! Which is allowed! And I am getting a wall-full of shelving units without damaging the wall by installing tons of shelving.
As for my studio equipment, I don't know what you use but I use the floor, my french easel as a drafting table (I put a wood board on it for that) and portable easel, my studio easel, and 2 large working tables.
In my last rooms I had to have all my easels folded away, and my worktables were, well was, 1 nightstand!
I knew I would be moving in here though, so I prepared! Here's what I did.
The first thing was get a HUGE floor cover. Do not make the mistake of using just any fabric or nylon. YOU WILL SLIP!! I HAVE BEEN THERE!
Plus, you want something that is easy to see spills on, easy to wash, or if it's plastic-y, easy to clean.
Everyone has their own preferences for a floor cover. In one of my old rooms I used a sheet, but it starts to smell bad quick.....especially after water media spills on it and the washing machine doesn't always help doesn't help.
Using clear nylon, or disposable table cloths is a
recipe for disaster!!!!!!!!!
From falling on your back to having it be near impossible to keep clean...all in all, trust me, bad idea!
Newspapers, even taped to the ground, wrinkle, smell, tear, are hard to see small drops on, so your socks get stained, and must be changed all the time.
I don't know about you, but after trying that for 3 days I got sick of it and wanted something more permanent.
An old rug (get it used, nice and cheap) works great, just make sure it is not too fuzzy or you won't see tiny spills, and make sure the colour is one where a paint spill would stand out on shall it happen.
Some people use long rolls of paper....the crunching sound when you walk on it got on my nerves quick! And it tears REALLY easily!
A light, medium thick fabric blanket, like a light fleece one, taped to the floor if you want it to not move, works great!

If you get a good colour, like a light sky blue, you'll see every drop, and it keeps your feet pretty warm, it's light and easy to drop in the wash, easy to replace, easy to fold or roll up...just.... easy. A great floor cover to use.
Then there's canvas. Yeah, actual rolled canvas. I have one big roll of un-primed canvas and it makes a great floor protector. Some people find it itchy sometimes if you paint in your bare feet, but overall, it's durable, doesn't tear and over time, looks like a nice work of art from some spills!
Then there's my personal favourite, an old, hard, plastic pvc shower curtain!
I like it because it feels harder, like a floor (I have carpet underneath) and you can actually wash it like a floor with a wet swiffer! Spills come right off the plastic with a tissue and some water. And oil spills just wipe right off.
It is extremely durable, easy to roll up, and doesn't tear. Depends on the curtain you have, they usually don't smell either, I love mine! But the blanket and canvas would have to tie to be my second choice.
As you can see, from years of rental I've tried most everything!
Now for the walls.
If you need them a certain colour, and you're not allowed to paint, or you don't WANT to paint someone else's house for free,

then if you are allowed to drill alot, something I did in one house and worked GREAT, is to cover the wall in cheap, white bristol board!
The walls were deep red, and we couldn't paint, so I bought some big bristols for 25 cents each, so pretty cheap, and covered the walls!
It was FANTASTIC! And reflected great light in the room. So that's one option, and you can get these in every colour you need, and every sheen: matte or gloss.
I chose white eggshell, and it was great.
If you can't do that, the other thing that works to cover the walls- from potential brush splatters of your paint, and if you don't like the colour, is hanging fabric directly on the wall.
I am doing that here. Because the room is not completely ready yet, I have some time to decide wether I want to cover the wall my easels will be against in canvas, or a white blanket, but I personally use one of those two. I have used both in the past and they both worked equally great.
The canvas just has a bonus that it let's you paint on your wall when you feel like!!!

For my worktable, I got a second hand one (if you're renting, get it all second hand or free, and as cheap as possible. You never know when you'll move again or where your next studio will be or if you'll need these furniture pieces then. Get them cheap, then you won't feel bad about selling them cheap again before you move, and then you'll also have less things to move into your new house,)
My worktable is huge, and I picked one that has an under-shelf, as large as the work surface itself, which is 4 ft by 3 ft.
What this did is eliminated the need for another huge storage rack. I get to use the entire under table space.
All of my clean canvases fit stacked underneath, and so do many of my paints.
And the edges of the table, have a gap, which I am using as a brush and knife holder!

Around the perimeter of the WHOLE TABLE, I am fitting old recycled yogurt tubs, with metal wire.
I am using one of those quick dry super glues to glue the wire to the tubs.
The recycled yogurt tubs will hang side by side all along the edges of my table. So again, brush and knife storage,
all of my brush and knife storage, without adding more shelving to the wall.
And the table has wheels, so it can stand anywhere in the room.
So; we've got the floors covered and protected, and the walls covered by fabric or bristol. So you're good in terms of coverage and now you can go crazy!
Since I believe you said you work in water media, I don't think smells would be an issue. My working with smelly gels and oils has become a problem here, and I posted a thread just now asking for help...so I can't help you there myself....... (as in worrying about harsh odours getting absorbed in the owner's carpets) but if you have any advice for me, please share!

To get more airflow, I had a ceiling fan installed in my last studio, which helped tremendously, and as for my studio easel...I built it recently out of scrap wood, and I designed it to be steady, yet the total floor space it takes up is only 90x40 cm width and depth. So really it is oretty thin for a studio easel yet can hold canvases any size and weight. It is in height, just enough to fit under a standard bedroom door.
It can tilt, and again, to save space, I am adding a huge taboret shelf to it, the length of 140 cm. So it is basically like a floating extra work table!
By putting wheels on it, I gave myself more flexibility. Having a dresser set against your protected wall, and leaning your canvas on top also worked for me quite well.
Once you have reviewed all the rental rules of the property, and what you are and aren't allowed to do, in 99 percent of places all problems are solved just by covering all the walls and floors of the room you'll be using with good, thick covers, that the paint won't soak through.
Covers for the walls and floor area of the room you will be painting in give you freedom. And then finding clever furniture ideas that are cheap, practical and work with your space.
I've spent most of my life living in rental properties, every place and landlord has their issues. But once you have a fabric or plastic cover for everything, you can go crazy and they can say nothing!
I was concerned like you when I first got into these rentals, but once you have the covers on the walls and floors, you're ok. And you can have complete freedom and no limitations. So happy painting!
And I hope I was able to be of some help!

