Baby moving in co-sleeper

My 17 week old sleeps in an “arms reach co-sleeper”. He moves around so much in his sleep. He doesn’t know how to roll yet. He just scoots, wiggles and shifts.

Every night, I place him down length-wise in the co-sleeper and he scoots and shifts so much that he ends up turning 90 degrees! Then he wakes himself up because his head is against the side of the co-sleeper.

Any tips on how to fix this? I feel like he would do the same thing even if I move him to his crib.