You can buy "self vulcanizing electrical tape" it is pricey when compared to the "plastic" stuff and does require a protective layer (friction tape) over it. I have a small roll of red and black.Eeeeww. Would rubber tape solve that issue? Or is it an electro negativity thing I can’t avoid?
Often used on motor leads etc to insulate higher voltages.
When all is said and done, I think the money would be a "wash" when compared to the adaptor with the plug in harness connectors.