I thought that I would share the pads that I recently made.
They are constructed of 2 sheets of 3/4" marine plywood, screwed and glued together. Painted them bright yellow (oil-based) so I am less likely to drive away without them. Rope handles are made from poly-pro (does not absorb as much water) and secured with screw eyes.
On top, I attached a plastic cutting board to serve as a wear surface for the jacks. The three holes near each edge allows the tool (on the end of a broom handle) to connect and push the pad under the coach and pull it out. Three holes so it's easy to find one of them. Red paint on edge makes it easier to locate the center.
I did not invent any of this - just assembled suggestions I found in various places.