Big "O", just ensure the area where the gasket sits is clean! You really don't need to do anything else. When installed right, the seal does the job. READ the install instructions carefully. Some gasket companies call for a 1/2' compression, while other companies call for 3/4' compression of the seal. The compression is done with those long mounting bolts. Snug them down after the unit is centered. Then, (I used a popsicle stick with a mark around it) tighten in a cross pattern until you reach the desired compression.
2703 Tow Lite
Bonita Springs, Fl. &