As a reader of the RV Doctor Column, you know my areas of expertise are focused primarily on the living areas of the RV; the major systems, components and appliances, etc. Rarely do I venture into chassis related areas since I feel there are many others better equipped to handle some of these readers' questions. From time to time, I'll ask some of my technically-adept friends and compatriots to chime in with a response for some of those areas.
And it also hints that the rubber tires on a vehicle do nothing to insulate you from a lightning strike. If the lighting has already traveled thousands of feet from the cloud towards the earth, another 6 inches of tire insulation won't slow it down a bit. It's the metal surrounding you that forms a magnetic field that helps bend the electricity around the exterior of the box. And even though you have windows in a car, there's typically enough metal in the windshield and door columns to make a nice low-impedance electrical path around you. However, don't stick your hand outside the window in an electrical storm as you could be killed that way.
Pop-up campers with tent fabric offer zero Faraday Cage protection, so I would never spend time inside one during a bad lighting storm. Plus if they're parked under a tree there's always the possibility of a big limb falling on your head with dire consequences. So pick your campsite carefully to avoid overhanging branches.