Here’s a trick my friend with 3 sons did as they became teenagers (it would not work at Pop, as the room limit is 4 people):
Rather than rent a second room, the “bidding” would start at 1/2 the price of the rented room. Each boy could out bid their brother for the lowest bid. The winner slept on an air mattress on the floor AND got paid his bid.
So if a kid really wanted to sleep on a mattress, he could. If he really wanted a few bucks for spending money, he could outbid his brothers and sleep on the floor.
No fights. No arguments. My friend saved a ton of money and grief on that move until the boys were grown.