Geez, every raised roof RV owner's nightmare. Sucks!!! (ok, there's the sympathy
).
Can you tell if it was damage from a collision or contact with an overhead obstruction,
or does it just look like old age/dried out caulking/sun damage?
Maybe start with a few questions here. I think it's free to join.
http://www.bigfootowners.com/
No idea if anyone else with a BigFoot has had the problem, but someone might have.
Maybe it's as simple as recaulking the leaking area, or the entire perimeter of the roof at the
body. It would be nice to know how the roof is attached to the body, before caulking it, to see
if there is any need for refitting it, or just tightening something.
Or try a Camping World or RV place or a local body shop, and ask them what they recommend.
It might not be as bad as you think, depending on what's actually inside the raised roof itself
(conduits, wiring, etc.).
Maybe try the current Big Foot company and ask if they got any schematics of the old class Bs
when they changed ownership? That would at least tell you how complex a major repair might be.
I contacted Roadtrek a while back for a similar question and they were able to tell me exactly
where stuff was inside the roof.
There must be a way to lift the roof off, and reseal it. (Maybe?)
Just some ideas. Hope something helps.
Updated thoughts about this.
Maybe try searching RVNet.com as there seem to be some fairly knowledgable folks on it as well.
http://www.rv.net/Forum/index.cfm
There are more than just class B-ers there, so the knowledge and experience base is probably larger.
Ron's thoughts about the crack repair stuff may also be worth considering.
If you were quoted up to $250, what would that be for? Pulling the rest of the seal/sealant and recaulking?
Maybe it's all you can do, without spending a fortune.