Thank you all very much, gentlemen!
Is that a sheet of plywood they're carrying?
Yep!
Actually, there are two sheets of ply* (one is under the Marston mat panels), a sheet of cement fibre board & a sheet of steel, three wood planks, copper, galvanised & poly pipe, & a steel I/H beam.
[*: I really like how these came out, considering they're painted styrene sheet.]