If you could find sliding doors of the correct height, you could install 2-3 of them on tracks at the top of the space and skip framing altogether. Another option, if you’re feeling a little less crafty could just be using those zig zag room dividers to separate the space and put up closet rods. At any rate I don’t think framing the entire wall is completely necessary since all you’re really looking for is more of a facade than anything.