In my last studio i had a small room and i never really tried to get a "room sound" as small rooms like you describe sound boxy or with the proper treatment have no sound at all. or its so short of a reflection it becomes part of the original sound.
| vudoo So far i use a 6 mic config where the overall sound comes from a pair of Shoeps at the corners of the room.
What i did was to mic everything close, use overheads and use the Lexicon for the reverb or room sound.
My new booth is still not built and i have been struggling with the size because I dont want to take up to much floor space.
The live room will Get a great drum sound and I will use the booth for a closer sound.
It will probably end up around the size of yours but i will have a taller ceiling so that will give me space to build a HUGE trap.