Newbie questions - basement studio design

Hi all, This forum is really a Godsend - I've been looking for something like this; and John Sayer's website; for a long time - I hope I found it in time! :) Here's my situation: I'm building a recording studio in half of my basement. The ceilings are low - the joists range from 78" to 81" from the sloping floor. The room is basically a long rectangle, about 11' by 35'. I've read Everest's books "How to Build a Small Recording Studio From Scratch", and the 'Master Handbook...". Based on my research so far, it doesn't really look like I could build much of a studio in this space - the ceilings are too low and the overall volume doesn't allow for a separate control room and studio. So I've been planning to finish the room with as much soundproofing and acoustic treatment as I can manage, and hope for the best. Ideally I'd like to record live music in there - drums, guitar, bass; probly overdub vocals. If I end up having to do one track at a time, so be it. Ok, so here are some questions: - I'm thinking of combining plenums for the hvac supply and return air ducts with wideband absorbers (basstraps). I'm imagining the plenums being floor to ceiling boxes against one of the walls. The air ducts will enter them at the ceiling, and there will be vents at the bottom near the floor. I was thinking of putting an electrical outlet in each one too, if it doesn't mess up the plenum or the absorber. As for the absorber, I was imagning a slotted helmholtz type, though Everest's books are a little vague on the specifics of these. Is this crazy or doable? - Any general design suggestions or warnings? Is this overgrown "hallway" shape going to be a problem? Thanks, Larry David