The big advantage of using North Light or in your case South Light is that the light does not move. Because the light is indirect and does not move with the sun, just set up your still life and see how the light falls on the subject with the window you have as it is now, things are not going to change.
Often with big North Light windows you have to block the light to make it more directional on the subject so your small window might be just what is needed.
“What peaches and what penumbras! Whole families shopping at night! Aisles full of husbands! Wives in the avocados, babies in the tomatoes!—and you, Garcia Lorca, what were you doing down by the watermelons?”
— Allen Ginsberg
Are you ready for a Journey
PS Critiques always welcome but no plaudits or emoting please.