Take a look at the Advanced Elements Island Voyage. We've had ours for three years now and it does work well. The air chambers inflate to 2 and 3 psi so it's quite stiff. We use the 2-way pump with a gauge to inflate it.
We made 6 "pads" out of 12" square 3/4 inch thick marine grade plywood,2 pieces thick screwed together with deck screws. Painted them white. We've been using them almost 20 years so they're holding up very well. We use them under our 6 point hydrauli...
