I have always been the one who says run the other way and the problem will be much worse than it is on the outside, However, this may be one of those rare instances when I may give it a second look. Mainly because if the only bubble is under the bedroom slide, that would suggest that water entrance was near the bottom of the coach, so the water would not be destroying the whole wall, but just a very low portion of it. It really depends on how much wall there is below the bedroom slide. I'm assuming not much, so that may limit the damage to something repairable. It should however significantly effect the price. There will still be a significant amount of work to fix it, but not insurmountable like it would be if the damage was higher up.
My only secondary concern would be that if there is water damage in one area, then how good of a job did they do putting the rest of the coach together. I would be inspecting it very, very thoroughly.
IRV2