I reconstructed the fiberglass trim. Then placed a hard nylon cutting board (from supermarket; cheap and super sturdy) as backing plate and bolted the motor right through with ss bolts, which were cemented with 3M 4200 like beamreach described. I used a 3/4 in HDPE plate and ss washers as backing on the inside. Been more than 2 years like that and looks super; no more headaches with cracking the trim, etc. Nylon cutting boards are excellent for this job, but require a slow-cutting implement. Jig saw and table saw cause a lot of melting as they cut through. Cheers, Albert