I would suggest using the highest teeth count that you can find. In addition put painters tape over the area to be drilled and then once the center bit in the hole saw and the teeth have made contact, remove the saw, go to the underside, tape that area and then line up the center drill bit with the hole and drill just deep enough from the back side to cut into the fiberglass to prevent blowout on the back side. Now go back to the topside and continue driving through. This should make as clean a hole as possible and prevent the backside of the hole from blowing out as the bit goes through.
Good luck. Every time i drill hole in something nice, my butt puckers a little too.
Jim