Two 4'x8' sheets of 3/4" plywood and one 4'x8' sheet of particle board (kind of remarkable how much more particle board weighs) - I had a hand truck and a ladder to bridge the 8' distance to the back post of my tandem. One of my kids at each end as a pilot bike. We took it slow up even small hills, and downhills were out of the question!

-Will