Sailboat lightening strikes illuminate how random and chaotic lightening is. USBoat keeps some statistics on this, just as many grounded masts are struck as ungrounded, the same story for static dissipators. Damage ranges from very little, to complete loss of all electrical equipment, to hundreds of holes blown in the hull and sinking.
In a camper, pobably the best thing is to park close (but not too close) to something a lot taller. A jack lowered to the ground is probably a decent ground for a lightening strike (short air gaps are no trouble for lightening), but getting the 100,000 amps or so to go from the frame on your solar panels to the jack is not an easy thing.