The civilian Bantam trailers had either sheetmental "wings" to reinforce their tailgates, or angle iron supports.
On this website
http://www.film.queensu.ca/CJ3B/Hubb...rs/Bantam.html there is a link to the post-war Bantam BT3-C models. Check out the tailgates and the two kinds of supports.
I have a later model BT3-C I'm rebuilding. Not going to do a restoration on it because it needs a bit too much work for that. I have the later broad sheetmetal supports. Hopefully they can be salvaged. The bottom edges are rusted and torn around the holes for the lights. I'm going to use this for a utility trailer. Still looking for an M100 or M416 for use as a camping trailer.
If you go to this thread
http://forum.ih8mud.com/trailer-tech/109913-pics-wanted-your-tent-trailer-setup.html and look close at the Alf's red trailer, you'll see it's a Bantam BT3-C civilian trailer with a tailgate.
Further down, Exiled has added a rectangular tailgate to his green M416 trailer. On Page 2 Exiled shows a closeup of his tailgate latches.
Still further down, Snook has added a rectangular tailgate to his white M416 trailer. But, take a closer look at his trailer, in the location behind the bottom fender lip, the chassis and the rear. He added reinforcing step plates with angle iron and expanded mesh. From these, he has struts running up to support the sides of the trailer after cutting a tailgate into it. Nice job. And the steps deflect objects that might wreck the fenders.