i would think it almost impossible to burn up cards or starting boards. because they are all 12 volt
and fed by the univolt and battery. batteries make good filters.
if a campground was on the same line as a large industrial plant such as a smelter or something with a large electric furnace, i could see problems developing.
more likely, a bad voltage regulator on the line could cause a + or - swing of 10%. still not enough to wipe out electronics. line capacitors can cause similar problems.
in the end, not to automaticly take the power company side. i would suspect the campgrounds wiring. however, power companies can and do screw up!