Aren't you glad to see you're not alone??
I do have some build up at the bottom of the front window inside that drips down when there's snow melting off the roof, but that couldn't account for the moisture under the sides the way it is in patches. I'm still wondering if it has something to do with that plastic(vinyl?)-bottomed mattress. May be a combination of things, but it sure can accumulate a lot of water under there. I'll try the slats, and if I keep this lovely little motorhome, maybe I'll find someone who can take that front window out altogether. Board it up with duct tape myself if I have to! This living in a camper in the winter has taught me a lot - holding tanks freeze!, an old furnace is NOT worth trying to fix for the 3rd time in 8 days - it's worth the big bucks to get a new one!, the little curtain between the cab and the camper can be replaced by a thick comforter, and weather stripping is not enough at the bottom of the door!! Oh, and the propane tank is waaaayyyyy too tiny in these Toys, and just because the vendor's meter isn't working doesn't mean your tank hasn't been filled - tho you can't be sure because your gauge doesn't work so you have to burn it off before the repair guy can take a look at it and you find it WAS filled because it's taking days to empty (so you got a free tank of propane).... But even with all those happenstances, I am having quite a fun time. Hope all of you are, too. And I thank you all for sharing your knowledge with me. This is a good group.