Hey Allen...Not 4 days ago I just asked my carpet guy doing our motorhome were getting ready to sell about this...He was contouring carpet around the wheel
wells and fire wall with contact cement so I asked about headliners in boats myself....he said the stuff from 3M was very good.
When I told him I already tried that myself with horrible results, he asked me point blank if I cleaned and prepped the fiberglass
down to a finish clean enough for auto body paint
Well I had to answer NO!...I had left old glue and all kinds of sin under there to hide..
He said there in lies your problem...it has to be that
clean or it will fall off like what happened to me.
The only other thing I thought about doing was glueing in some 1/2 closed cell foam with a more structual adheasive like outdoor carpet adheasive...That would give you a nice clean surface to start over with....and some insulation/condensation relief as well..
I was/am already way upside down in that boat rebuild
so I have just sold it as is....but I think it would work....Trying to clean off all that old glue overhead like that would be a killer.