Re: Should I enlarge the subject of this painting or leave it alone?
Sorry I'm late to the party, this is a cool forum!
The only change I'd make to your new composition is I would make the joshua tree a bit larger and taller, just a bit, move the yucca up and to the right just a tiny bit and the van down and to the left a smidgen so it's not directly underneath the sharp cut gray mountain and will give the yucca a little more breathing room. That will give you a downward triangle of the 3 major elements that would lead you around to the mountains in the background.
I would NOT get rid of the blue mountains. They are integral to telling the story of place.