Building a wall in a rental property
I'd seriously consider a Byōbu, more commonly known as a &quot;Japanese folding screen wall&quot;. Something like this:
The first decent example picture I found happened to be from etsy
You don't have to purchase one (finding one for your 9-foot ceilings may be difficult). However the &quot;folding&quot; aspect - i.e. the zig-zag footprint will allow it to stand on its own.
You can cover the &quot;panels&quot; with drywall, fabric, paneling, or whatever suits your mood. The advantage is that you don't have to attach it to the floor or ceiling and, therefore, won't cause damage to the rental that will need to be repaired before you move out or risk losing your damage deposit.
Since you're willing to spend the money on lumber &amp; drywall and dispose of it when you move out, there won't be any significant additional &quot;disposable&quot; cost in building the wall this way instead.