Have you tried these scenarios to see, or are just guessing the results will be as such? I only ask because
sometimes what seems very unusual, ends up working.
Years ago, I was in one 6'9" high basement, with a Sony 1292 crt pj. It was low, to put it mildly.
I was eye to crt lenses. Yet it worked fine once you got over the uneasiness of having a 250 pound
projector hovering above. The owner even had a second row with a 6" riser behind. Excellent sightlines,
and while it looked different, it worked very well watching a movie with the lights off.
Another unusual set up I've seen, was the JVC RS1 and Draper HighPower combination, where the projector
was mounted mid room height on the High Power screen. When my friend told of his new set up, I had to
go this since I couldn't see this working. And since you have one row of seating, the projector might just
work on a stand (or equipment rack) right behind the seating. Might work as a port hole solution with the screen
on the bottom wall.
Another possible scenario might be to use a front surface reflective mirror to lengthen the throw distance, to get
a bigger screen. ( Much like a rear projection TV ). Never seen this first hand, but I have heard of it being done.
A little digital projector over the seating, might be a very good location.
A rear projection setup might also work. The trick is finding one cheap...