Personally, I think you're stressing for no reason, but maybe that's just me. I've never heard of anyone climbing up on an RV that they didn't own/have a reason to climb up on. There's nothing valuable enough on the roof to be attractive to thieves, and there are certainly much easier ways to gain entrance to the inside than dropping in through a 14"x14" vent!
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You don't stop playing because you grow old...You grow old because you stop playing! 2004 Itasca M30W