Regardless why and how the incident happen, I would try to contact camper manufacturer for tank advise.
With so many different designs, you simply can't assume anything.
I did work on my water tank (the fill hose was caulked with loose clamp on it) and in my basement camper, the tanks sits under the small front window - taking about 5 screws from top cover shows it all, although with all the wiring and plumbing it might take some time to pull it out.
Quite often those tanks after few years become obsolete, but you can use one of those bladder tanks sold in marine places.
