Yes you can sleep in a poopy diaper.
I sometimes will sleep in a poopy diaper and it's never been an issue.
If I put on a diaper and I need to poop and it's about bedtime then I just crawl into bed with the poopy diaper and sleep just fine.
Never got a rash from sleeping in a poopy diaper but if you're worried about getting a diaper rash from the poopy diaper just apply some diaper rash cream to your diaper area before bedtime.
As long as you change the poopy diaper in the morning or within an hour of waking up it should not be any problem sleeping in a poopy diaper.
A lot of toddlers and babies sleep in poopy diapers at night so it's not really an issue for adults or teens as adults and teens have tougher skin.
I've also slept in a wet diaper as well.
I sleep good wearing a poopy diaper or a wet diaper.
I also love sitting in a poopy and wet diaper or even just a wet diaper or a poopy diaper.
I've pooped my diaper in stores before as well and just walked around in it and nobody seemed to notice and it's very fun to just stand there shopping and poop without anybody realizing it.