The black gorilla tape. Like this one. I saw it once on the youtubes being used instead of official tubeless tap as an alternative and thought that'd work well too for regular rim tape. I've used it quite a bit, seems fine.

I simply splice it at the begining to fit whatever rim I am using, and kind of rip and tear as I go around. Hopefully that makes sense, I can take pics of what I mean if you need it.