Thanks David. Yes I agree entirely and I expected to hear that it just isn't done. However my frame of mind is to "treat the disease" rather than try to put lipstick on a pig with microphone technique. It is frustrating to try to work around terrible sounding rooms.
That LENRD product looks great. I think that's more or less the idea -- a way to get some kind of baffle in there on a stand that is quick, clean, and easy to deploy without cluttering the whole room with c-stands. It would be improved with another smaller triangular baffle on top of it, at a 45 degree angle, and put in a corner.
Alternately, it would be great if there was a way to just slap materials up against walls without damaging the paint or poking hole, but I can't think of a way. Magnets don't stick to drywall. Again, I'm talking about situations where you walk into some house or office.