What was actually wrong with your own design ?
Thing is you see, you're an engineer used to fine tolerances.....but fabric stretches, it sags, it folds. If you don't want that you need to add structure to it, and unless you use the seams to create that structure, the bones if you will, then you're into the realms of channels and blow up balloons or rods. Tents are by their very nature a bit 'fluid'.
I think, if you can get a mesh inner that would suit well, then buy that and attach on the ripstop parts.
@slimshady 's idea is probably the most realistic solution.
This used to be the kind of thing that we'd ask
@bilmo-p5 or Eric methven to do, but they're both no longer able apparently.
You might ask Gilly ? very capable lady, very clever, thinks things like this out, and she might well think it a fun project ?
M