Home mix room

I've decided to set up a room at home to do mixes and some recording (mostly direct guitar/bass etc) I'm already mixing in here and achieved reasonable results, I think (hope?) some basic acoustic treatment will help make mixing easier. I live in Canberra, Australia and I rent, so anything I do must be undoable. The room is 9' wide, 11' deep and 8 feet high, I'll attach an skp when I've downloaded sketchup and figured it out! My budget is pretty limited, so I was going to start by making some rockwool absorbers like so many others here have, maybe adding clouds later. I actually have another spare room (and a tolerant better half) so down the track I may build a vocal booth in there, or go all out and treat it as a small live room, mostly acoustic treament rather than trying to soundproof it. I've recorded a full drum kit (with double kicks!) in there and it sounded passable, but was pretty ugly around 100hz. Anyway! The main reason for posting was to ask if anyone had any opinions (good or bad) to share on the design for a trap posted here: http://www.soundonsound.com/sos/mar06/a ... diosos.htm