Hi, onsies are a great idea, first you need to put them on, feel where his tail is, and use a marker to mark the spot. Then take them off and cut a small line, when you put them back on, his tail will pop out. That's the way I do it.
Good luck! Hope he heals fast!
Oh, Love Wookie's name, my kids call Princess, Wookie as a nickname
Gina & Princess