How many of us are there? Owners of Dodge based RV's?

Adhesive lined (thermal plastic, a form of epoxy) heat shrink tubing. Available from several manufacturers and multiple sources, mostly catering to the marine wiring market.

I prefer Ancor, for wire as well as the heat shrink tubing. http://www.ancorproducts.com/en/products/wiremanagement/heatshrink

The adhesive/epoxy melts while you're shrinking the tubing. As the tubing cools, the adhesive/epoxy hardens, sealing the wire splice or connector crimp.