Yep I gotcha. I mounted inverted on mount 8" off ceiling at 15' and filled my 90" screen 10" fromr ceiling to top.
Brother A has his 12" or so from ceiling at 12' and has his sitting right side up in a cubby 20" off center. He was able to shift and fill his 92" screen at 15" from ceiling to top of screen.
Brother B has his ceiling mounted inverted with same mount and height as I did and was ok from 13' or so for 106" screen.
We tested brother B's situation using a step ladder first and went from there. The Epson is remarkably flexible it turned out. So long as you mount the lens below the top of the screen, you should be good with either right side up or inverted orientation. The further you mount from the screen, the more shift distance available. (Lense shift is a fixed ratio but shift distance increases with throw distance.)
The epson also exhausts out the front, so you can jam it against a wall or in a cubby/shelf without issue. Just be sure to make sure it has breathing room on sides and not sitting on plush fabric or carpet.
