Plywood decking installation.  Extruded (dense foam) is next.  I re-configured the removable sections to a lighter weight, simpler design. I also revised the construction of the end connectors to eliminate complexity and weight.  Even at over 60 inches long, 1/2-inch plywood with multiple stringers of 1 x 2s screwed on edge has a lot of rigidity.  They bolt into the main frame.

I changed the upper connection to that shown below.

This is the simplified the north end connector with wood brackets and spring clamps for the road bed.  I may go to bolts but the clamps are very K-I-S-S friendly.