we've got a custom cover, and will only be travelling about an hour in light rain. I usually try to avoid it, but I'm considering it for the holiday weekend.
I hate pulling in the rain but sometimes it cant be prevented. I prefer to keep my boat covered and I just wash it after I get to where I need to go. No problems, other than having to wash off a little road grime.
we pulled the boat from Washington state to Texas.. going through rain.. lots of rain.. snow and dust. We towed with the stock supra cover. everything went fine, then gave it a thorough wash when arriving in texas