[Nabeshin]

But if you complain at the end of the stay, won't the hotel realize you were the one to pee in the bed? Doesn't make a lot of sense, sounds like a day-one complain to me

It's not difficult at all to justify It.

Simply say the urine was towards the end of the bed where your feet are positioned during sleep, hence It wasn't noticed until a later period. Alternatively, you were experiencing a backache, so you turned over the mattress, only to find urine thereafter. Do It on the second last day of your stay - just to give It time to dry.

I can think of 20 more excuses that will easily manipulate hotel management.

Ah yes, in a non-common spot it would make more sense
Can't see myself using this but it's still an idea