As you know, in a perfect world, those speakers need to be pulled out more. Can they be moved for critical listening, and then put back? The thicker the absorption behind them, the better. If large corner tube traps are out for the corners, then see if you can get approval for triangular ones at both floor and ceiling.
In my room, the couch gets moved, coffee table is moved, Love seat gets moved, absorbers go into place, diffusers go in front of the TV and to the side of the speakers--- all before I sit down to spin some vinyl. Then, everything goes back to normal to make things more presentable. But altogether, it's no more than 3-4 minutes to assemble and disassemble.