I don't have fibromyalgia, but have been on several retreats that use "those dreaded camp beds" :-). Several people bring some type of foam memory topper and/or an air mattress (either a thin one to use on top of the bed or a nice thick one to put on the floor next to the bed). Also - most people bring some type of cushion(s) to use and some even bring their own chair from home. I don't know if any of these cushions/toppers were from fibromyalgia or just plain comfort, but they're an idea if they help.