Install a Maxxair MaxxFan on my Roadtrek - roof strength...

I didn't think about it when I ordered the fan, but can the roof support my weight?

I installed a Fantastic Fan in my trailer and I used a piece of plywood to distribute my weight on the aluminum roof.

Since the roof on the Roadtrek is a fiberglass shell, I'm not sure I should get on it at all...

Aargh...

Anyone done this or know what the procedure should be?