Like Steve, I think having an under-sized winch on a heavy truck camper rig could put one in a situation where some part of the winch may fail...anyhow, that's just my opinion.
Only if you over work the winch. There is a huge difference between trying to get a bogged vehicle out and one that only lacks sufficient traction.
The winch motor will only pull so much and is designed to be the weak link in the winch. The motor will not pull more than the rest of the winch can with stand.
I would rather have the undersized winch on my truck than no winch at all. In just about every situation where the winch could be used, it will be enough to provide that little extra pull that my tires can't to get me out of a situation. At least in my case, it's for the "whoops" moment, not the "oh I have a winch if I can't make it" moment.