Home made Shooting Mat
Here's how I made a pretty nice shooting mat for prone crop damage shooting and field hunting. I took a pair of leaky 5mm neoprene chest waders, cut the boots off, and cut them down the center of the back and down the back of each leg. Then I folded lengthwise so that the black felt liner is on the inside, the camo on the outside. The result is an approx. 2' by 5' rectangle of 10mm thick neoprene, camouflage and water proof. I cut off the suspenders and the chest pocket/shell loops, but you could re-attach them for carrying a few small items. I rolled it up like a sleeping bag, and used the waist belt to cinch it down. It attaches to the bottom of a backpack easily, and doesn't weigh much.
Good way to recycle your old waders, and it will keep you up out of the mud. More comfortable to lay on than a tarp.