Why buy a spare part, pay a lot of money for it and also burden the environment with shipping if you have a 3D printer :D
This was for my Hobby Prestige 1988 but you can use it for every other caravan. The spacing between the bolts are 185mm.
I screw a M6 threaded rod with a bit of good glue in. The length of the rod seems to be different on several caravans. So measure it by yourself.