If you need separate private spaces, half walls won't do it. If you just need separate functions, why not use furniture pieces to divide the spaces, storage pieces, free-standing closets, etc.

Can you post some pictures of the area?

I don't see why you couldn't build nonloadbearing walls to section off the area, but of course it's going to block the sun. Half walls won't work unless you just want to section parts of the room off, not provide privite rooms.

You could also get some bifold doors to make room dividers with.

At least three quarters wall.