I just did it to try it out. My DS27mo had a lot of fun in it - I hung it low to the mattress so he could fall out (he's really cautious and doesn't like being tooooo rambunctious). He basically sat in it and fall out sideways. When he laid down it looked pretty comfy!
Then I put DD4mo in it...but it was too low for her. She was scrunched. So I tied it tighter and it was basically horizontal. She was squirming and arching her back but didn't fall out.
So if you're doing it for beds, OP, make sure you make the hooks close enough to the floor that your kids don't need ladders to get into their beds