Couldn't you just use Eternabond tape? I can think of other similar methods but without a photo of the switch, it is very hard to make a really good suggestion.
If removal of the switch is probable in the future, I'd use Faston connectors on the switch with wire leads, seal with epoxy or resin and splice a Packard fitting on the leads and the original wires with self-sealing butt connectors.
It will last as long as the RV. Del City has both,
butt conectors,
Fitting w/pigtailsI looked up Delphi 66 and it is a Delphi Packard fitting. You ca also google auto shops with Packard Fittings.
