Back when I had a trailer, my standard auto policy on the truck covered damage that the trailer CAUSED if I was in an accident while towing. It provided NO coverage for damage to the trailer while it was parked.
I picked up an additional policy on the trailer to cover it while it wasn't being towed - hail, fire, flood, etc.
If you're in a position where a 30k loss wouldn't hurt, then don't get insurance. If it will make you lose sleep, then get the insurance.
Either way, find out exactly what your policy covers, and when it is in effect. Your auto policy agent may tell you "sure, it's covered!", but might be only when being towed, and only for damage to others, leaving you with a pile of pieces.
Rob - Solo Full Timer
2017 Winnebago Travato 59G
Former 2006 Mandalay 40E