Hey Rez. Just resplice the wire ends with regular automotive eyelets and attach them to were they are supposed to go. Then either get covers for your grey and black tanks to keep the dogs out of there. Or, spray they area with bitter apple spray (found at your local pet stores). Saturate it good. The next time the dogs try to chew on the stuff they will get a nasty taste in their mouth, and likely wont mess with it again.
I too have to replace some trailer holding tank wiring. But thats mostly due to it being 20 years old. And I will be repairing it exactly the way I discribed.
Thtat is my next step...my buddy offered to help me out...he know's his wiring. I just can't figure if the fix is THAT easy why wouldn't the RV place have done it??? They had a paying customer...there's got to be more to it that I'm not getting!