Being locked in diapers is very fun.
I have a pair of locking plastic pants and I locked myself in the plastic pants for 3 days and mailed the key to myself.
So I was stuck in a wet and messy diaper for 3 days until I received the key back in my mailbox.
So you could try that as it was really very fun however I only actually pooped the diaper on the last day so I wasn't in poop for very long.