Personally, I like Shibari. You can order it on Amazon for 10 bucks.
Wipe off before oral? That’s more of a preference thing. I assume you are talking about anal to oral? I suppose I do a quick towel off but I really wouldn’t care much either way, but that is because enemas are usually a part of it and I often will have my tongue inside her ass anyways.
Besides, I think it is extremely hot that a girl would trust me in that way, borderline degrading, and most importantly, of course, I’d look first and I’d never put a dick inside her mouth with anything on it. But this is a hard limit for a lot of people, and once was for me too, so I get the “no way” reaction that many people have.
At some point, you just say “fuck it”, and go with the moment.
Last, if you start w oral, thick spit is fine.