I read what the others have written, but I make (made - before the depression) a living working on boat electrics (Same-Same). You have not said what you have. You call it a camper and that is pretty wide open.
That fact that you put that much water in a pair of GC2 and you are seeing a lot of corrosion, makes me want to agree that the bank is toast, but that should wait for the actual data.
If you left the unit powered up and it does/did not have a modern four stage converter/charger, then the bank is probably toast. Do the whole diagnostic first.
But before you go and buy new batteries, go shopping for a good converter/charger (Progressive Dynamic, Xantrex or Iota) and get the smart 4 stage version. This will cost you about the same as the batteries. The big issue is that you will never need that much water again and the batteries will be in good shape for years to come (assuming you don't kill them by over discharging them). A pair of GC2 will like a 45~60 amp charger. But you still should not ignore them.
Matt