How to properly degrease the freehub engagement ring pressed in to the hub without spraying the degreaser (brake cleaner) on to the cartridge bearing seal? Usually/previously cleaned the engagement ring with q tips but since it's impossible to clean all of the edges in this way then there is no other choice but to soak it in brake cleaner instead. One option is to smear some silicone sealant around the bearing seal so that it can be easily removed. Another option is to stick a washer on top of the bearing using the same silicone sealant, but since sometimes it can result in strong adhesion then it might lift the seal upon removal of the washer.

You're quite the over-thinker aren't you? Just clean it as well as you can and move on. It's never going to stay perfect for more than a couple rides so it's just not worth worrying about.

I'm going to try out different grease which is not based on hydrocarbons, so it has to be cleaned a bit better this time, otherwise the advantage of heightened surface wetting ability of PFPE greases such as Krytox GPL205 might not be used fully.

Ok, whatever you say.

I think you are overthinking it too.

But anytime I want to get that last little bit of oily residue I'll rinse or wipe with >90% isopropyl alcohol or use acetone. Acetone works the best but it'll ruin painted finishes and many plastics.