How can I get my bf into buttplay?

My boyfriend LOVES spanking, but has never tried any other buttplay before dating me. He's trying hard to be a great sport by licking/fingering booty at my request, but is still largely uncomfortable about it so I haven't really pushed for anal. I want that and more but don't love the thought of making him sick. Fortunately I have a lot to work with because he is otherwise really kinky and enjoys being both dominant and submissive. How can I make it sexy for him?