OK, he has told you his boundaries. Options are: You convince him to move them, or you move yours, or you cheat (with concomitant risk), or you pack up and get out of Dodge.
My choice (and it's just my personal one) would be #4. It would hurt, but I've been there and it didn't get better - I kept it in my pants and he got all jealous anyway and the end was just ugly.
But if you're inclined to #1 and/or #2, I'd look at his boundaries carefully.
...as long as we're both involved... Probably that's not going to change, but if it does it will likely be a gradual process. I wouldn't push it.
...and it's safe... This is where I think you have some room to change things. Fact: There is no safety this side of the grave. You could be hit by a bus! (thanks Cher!) PrEP and vaccines mean your risk of getting something incurable and nasty from sex are really pretty low. Getting something curable is less likely with condoms, but as someone who has acquired STIs more than once while using condoms every time for anal intercourse, it's pretty easy to do anyway. Education may be your best strategy here.