Living in the middle of tornado alley, where big thunderstorms are frequent for a 3-4 month season, I keep my RV in its storage shed when storms are forecast. We do our RVing and camping in the lulls between the storms.
Still, I've been caught, and even not being under large trees, I've had branches blow onto the top of the RV. Since my roof is a fiberglass sheet, most I've gotten is scratches. The storms that take apart these trees are often 50-80 mph wind gusts, the branches don't fall straight down, making it really hard to pick a spot in a forested campground.
Our commercial RV parks tend not to be forested, for storm reasons. Trees are more popular in public campgrounds where campers need the shade, but they also don't go out and set up their tents when thunderstorms are forecast.