Wow!! $11,000 - for the whole camper? Might be better to trade for a different camper. '07 being that new sounds like a factory problem.
We have a similar problem with our '06 and it was mostly around the large
kitchen window from the bottom of the window, down. I peeled off the wallpaper and it dried up real quick, but may have to take out the window
and check it out completely. I re-caulked the outside of the window where
it looked like it could've been the problem. I called the factory about wallpaper and he said that the panelling comes in already with the wall covering on it. So we've used some border to go over some of the area
and I bought some of that commercial rubber baseboard from Home Depot
and cut and placed it under and around the window to cover that area up.
Looks like a backsplash - being a kitchen and all - might be an improvement
actually. As long as there is no more water/moisture getting in.