A very slim ring spanner that was sawn down.
Gave mine away with the bike when I sold it.
Amals often warp like that mostly due to ham fisted gorillas over tightening the mounting nuts.
Sometimes you can get them flattened out but often not.
@puffernutter The Body Roller you have linked to attaches to the wheel hubs.
They in turn are attached via the suspension to the main chassis.
So the only weight on the body mounts is that of the body.
Without sight of the condition of the body, I don't think you will have any problems at all...
Contact Counter Rivet Ltd on Facebook or via https://www.counterrivet.com/
AKA Guy Ropenall,
He can repair British Army tents with patches of original canvas.
Do you have a wheelbarrow ?
Do you have something to put over it to keep the rain/snow/sun (delete as appropriate) off the contents of the wheel barrow ?