In any RV, it's important if you want to use the tanks in cold weather that the dump valves be able to function. In your C, are the dump valves in a compartment or hanging out the bottom? That would be a concern. The tank heaters only need to keep temps above 32º, so they can work on un-enclosed tanks, but it's better if they are enclosed with dump valves and plumbing in a 'wet compartment' that can be heated.
Bob & Donna
'98 Gulf Stream Sun Voyager DP being pushed by a '00 Beetle TDI