Sleep Training A Climber

Any tips on sleep training a 7 month old who just wants to climb & stand? We have already lowered his crib to the lowest setting before toddler bed and can handle the crying but can’t handle him banging his head on the back of the crib or the railings. When we put him down for naps or bed he gets right up on the railings. I try to leave him as long as I can stand but he inevitably falls especially the more tired he gets and most times hits his head. So it turns into a game of put him down, he gets up, we put him back him down, he gets up until he wears himself out and stays down which can be an hour. I can’t find any advice on this and we really want to get to a place where he goes down easily!