Many metropolitan areas have an "UFO Outlet" upholstery jobber that suppplies home and commercial users with a variety of materials depending on thickness and firmness needs, and can recommend an expert cutter if needed. DO NOT put yourself, your children, or your dog on anything resembling a hollow-tube air mattress, unless the manufacturer gives you an R-value of 5.0 or greater. Those things are only intended for use at home in heated enclosures. Camping should be comfortable and restful, don't torture anyone by using an air mattress. Mom's Alegro had one inside the sofabed, but the RV also had a huge furnace and two big AC units, LOL.
