The platform for my Willys wagon wagon is going to be appox. 5'x5'. I did not want to splice 4X8 plywood together to make 5'X5' so I found 5X5 Baltic Birch, 9 ply panels at Woodworkers Source. A little trimming on the sides and I will have a seamless platform. Anyone run into the same issue, try the 5X5 panels.