Period sex!?!

I've talked to my partner about having sex on my period and as a typical male he is completely grossed out about it. Sometimes he says "okay but you have to clean up afterwards" and I get so offended by it, yeah I know period sex will be messy but I find it helps with my back aches and cramps. I have tried explaining it to him that's it's going to happen every month and it's really not as gross as it looks But what I'm trying to ask is there any tips for period sex ? Obviously I won't pressure him into doing it but when the time comes and he is comfortable with it I just wanna be prepared for it. So yes ladies please leave me some tips on what to do and how to make it as mess free as possible