Crib--Stuck

Working on having my LO sleep in his crib when he turns 6 months. I have been trying to put him in there for naps (he hates his crib and NEVER slept in it before).

I was right outside the room then I heard him scream and cried hysterically. Ran in and his whole right leg was stuck in between the rails and it took me a while to get it out. He is a big boy so he got them chunky legs.

I know it is recommended and advised to not have bumpers at all to reduce the risk of SIDS. My boy rolls and moves so much that I don't see him sleeping there at all without getting stuck and hurt.

Any advice?