I would assume that the waterproof/weatherproof p&s cameras don't offer the lens flexibility you need.

I agree with Matt with respect to "throwaway" bodies. Nikon 8008 bodies are extremely cheap. So are MF film bodies like the SRTs and equivalents. But the real issue are lenses, none are particularly inexpensive (except perhaps the "can't give them away" manual third party 80-200 type zooms).

Will most/all shots be at infinity? If so, you could wrap the lens in some sort of plastic wrap for some protection. There's probably a more elegant commercial version of this.