Hey, i don't think you are going to fit a mattress in any of those. You did list some good choices. I would steer you toward the toyotas or the Honda CR-V. The president of Honda even drives a CR-V
also, both the pathfinder and xterra have had problems with the engine coolant leaking into the transmission causing a milky fluid and premature transmission/clutch failure. U can review this fact on edmunds.com. Hope this helps. Good luck