I get it..... my wife married a career musician and motor nut so she gave up in the beginning when it came to the garage, guitars, amps and me stealing the spare room for dedicated audio.( studio is 100yrd from the house lol) In the ht room "family room" i am working on the treatment now it rings bigtime (slap echo) 24'x28'x17' vaulted ceilings. she is down because she can hear the difference .If you can sway her try somebody like gik and just browse thru they can take pics and imprint them on the panels.Who can say no to a family pic? lol. I have and still remain a fan of the better sunfires and honestly i may be in the few but i feel a smaller driver is faster and more accurate.Thats why i dont have big drivers in my spkrs like many . Sometimes if not almost all the time when ya take a crisp tight spkr and put a larger sub with it there is a distinctive separation between them imo .i think when you get that hrs8 you will be shocked it throws like 1.5" ! mess around with it .I know the purist are going to interject but straddle a corner facing out ,a foot or two ,try phase switching,and god forbid lol turn it around about two feet from a corner and face it .try it along the wall close and a cple feet out.these changes will be significant some will be boomy as hell somewhere in there it should just melt away in your system .If your are like "dam theres the low end i'm looking for maybe you can mark it somehow and only place it there when the wife is away and have a serious session.i used to do that in one of my old setup yrs ago. Get another 8' sunfire it will be tight and rip in all but the most demanding situations and there tiny.( wife approved).although for me i would prefer two 10" in the perfect setup .sorry but your setup is limited by different obsticles with all due respect. I am lucky to have a 13'x16'x10' room. the sunfires are easy to sell if you choose a different path ..jmho
good luck