I've used the coleman queen size for the last two years, and haven't had a problem, but then it is just me on it
The cot or futon sounds like a great idea, but the futon is heavy.
I use a full size futon. Yes, it is heavy, just like my tent! But I drive a pickup, so I take a 1,000 lbs of crap to the playa. And the futon is just slightly smaller than the bed of the pickup, so it makes a nice "lid".
The futon, with sheets, pillows, etc, in my big tent makes for a nice apartment on the playa.