my nails are very short,it would feel so good for me to rub that hole and slip the finger in.i bet your ass is red hot and tight af.

I love the full body massage exchange idea. Use warm coconut oil. It's very slippery and has no smell. Massaging with lotion is crap, because you'll get nauseated by the smell before you're through, and never want to try it again. Pull out plenty of sheets and towels for this. Be prepared to make a mess that can go straight in the wash machine. Leave no excuse for squeamish distractions about soiling the mattress, etc.
Rule #1 is that each person must get touched thoroughly, deeply and absolutely everywhere. This means nothing half-assed. If it gets touched, it gets touched thoroughly. Couples married for many years still will get a lot out of this experience, because we still carry half-unconscious ideas about where and where not to touch. This breaks the barrier.
Rule #2 is that each party must be audibly verbal with oohs and aahs. No feedback is the worst. So make it a rule. By the same token, if something feels too intense, feedback.
Rule #3 is that each person gets completely equal "me" time with this. There should be no confusion about when it's ok to just lie there and "take" and when it's time to just "give".
It works best if you both agree to refrain from cumming before each party has had their equal time. Men, if you come, I guarantee your partner won't get their due time. Don't try to cheat; It'll come back to bite you later.

You'll both learn tons from this and also open some new "avenues" for each other.

One last thing: Men do concern yourself with women's fingernails in your rectum. That tissue is paper-thin and tears VERY easily. Proceed with care. Cuts inside, no good.