Sounds like we've not been in as bad storms as others are describing. The worst was probably a thunderstorm at the KOA on the Canadian side of the Niagara Falls. There were tornado warnings if I remember correctly. We put all outside stuff in the truck or under the camper, then watched a movie on a laptop. My son (preteen at the time) kept his rubber boots on, just in case our camper tipped over...
Turned out the worst parts of the storm missed us, and the campground and other campers were all fine, so it was fun more than anything.