What about when they crawl?!

I also co sleep and my baby is 5 months old and getting around some and super close to crawling. we have our bed on the floor on top of a thing to prevent mold (it doesn’t increase the height) and a bed rail on the bed right now that’s pretty long so he would have to go to the foot of the bed to get off, we will see in the future if we need something else or not however they do make floor beds! It’s like a bed rail but all the way around

You could get bed guards if you're really worried. I think they just slide under the mattress and it basically turns your bed into a big crib lol
My baby would get to about half way and then lay down. Like sleep walking cause she wasn't actually awake so she didn't make it far. I just kept her in a onesie so I can grab her by the buttons lol
We also got a pack n play that she uses like a crib for naps and for when she goes to bed but we're still up. That way I didn't have to worry about her rolling off the bed. Now that she walks, she knows how to get off the bed safely but that hasn't happened during bedtime (thank goodness lol )

Floorbeds! Generally rails aren't recommended until at least 18 months I think. As soon as she started crawling we taught her how to get off the bed safely which took about a week. It also helped for when she started climbing everything because she already knew how to get down safely.

She has rolled off the floorbed a few times in the night, but we have foam mats on the floor so it was just more of a shock than anything and she was asleep again as soon as I picked her up.

You just want to make sure they can't escape the room in the middle of the night. We have a gate on the door.