just picked up an AC unit over the weekend. its the type that sits on your bow hatch with a canvas shroud. can these be left up there and running in the rain? i would only ever use it while on shore power. last weekend we had a big rainstorm come in so we put the camper top up and sat in front of a small fan but i was soaked with sweat. would have been good to have had that AC unit then but not sure if they are safe to use in the rain?