bh3585, try using a small tipped screwdriver to try the cover off as likewise we have same thing.
As for skylight cover, I get why David would like to replace w/ a clear one as the frosted one is IMO mearly for privacy. A clear one tho, again IMO, would seem to allow more light in thus in turn more heat into the coach.
Just FYI for those of you that have the same skylight as mine and will eventually need to replace the bulb. The outer ring twists off and then you have to remove the lens assembly to get to the bulb. The bulb is a G4 and the ring is really hard to twist off. When I say really hard to twist off I'm not kidding.