Really ...looks like a soaked tissue paper tarp.

We need to see how it fits on the trailer. No doubt it would work well in the load box of the truck but the trailer is the important question.

I was just thinking about the soaked tissue paper tarp idea: take your ugliest, most disappointing build (we all have one somewhere) and tarp it that way and voila! A cargo load. Crates are so yesterday so why not tarp an officer's staff car? A Bieber mini-sub? Justin Bieber? (Just kidding, sort of)

I didn't know the Germans used to transport their panzers covered with tarp, or with paper, as illustrated here. Only the warning "Geheim!" is missing.