[bushpilot]

in soft soil or warm asphalt (and even on concrete) i use 3/4 inch (marine grade) plywood...

I cut the plywood in 15x15 inch squares and have screwed several squares together...this serves a couple of purposes - 1) is spreads the load to prevent sinking or punch through 2) it increases the "reach" or potential height that i can lift the coach (if I'm on a steep incline) 3) it eliminates the need to run the jacks out to get the tires off the ground (when in storage).