I'm with James on the the bath fans. Even though they have brush-less motors they can and do fail starting fires when used as bath fans. You don't want paint fumes passing over that motor when that happens.
I question using the boat bilge inline blowers as well . As I understand it, they are designed as just that, blowers. They blow clean air down to the bottom of the boat to force gas fumes out the vents. Although they are brush-less will the motor spark if it fails from paint build up over the years?
That said there are bilge blowers with the motor outside the air stream that would work great.
I am surprised that 100 CFM would be large enough. After you deduct for filter and static pressure of the hose you wouldn't have much left.