Hunters Speacialty (self-inflating) air pillow w/strap over the top of the Lone Wolf pad. Not too much air, just a little to keep your bones off the metal. It distributes the weight better for better blood flow- so longer sits.
Buy two or three and test them at home during supper or on the couch for a 2 hour movie. Keep the one that holds air, and return the others that leak. I buy one every couple years - about $14.
I use it in the off season elsewhere: canoe, bleachers, squirrel sitting, and as a lumbar support in the truck. Just vary the air volume as needed. For compact storage or packing, squeeze the air out by rolling it up and closing the valve.