What to do if LO will only sleep on tummy?

JKTTC1

We've gone from the swing, to PNP, to My Little Lamb Seat, and now the RNP. Most nights LO ends up in the bed with us sleeping part of the night or the whole night. He likes to sleep on his side or tummy. We are starting to take some naps in the crib. I put him down 20 min. ago in his crib and hes sleeping on his tummy. I guess I'm wondering if anyone else's LO is doing this and what do I need to do?

BTW, he has reflux so we bought the RNP. He does some 4 hours stretches but every night is different. He also HATES tummy time but likes to sleep on his tummy???