I believe that the rear overhang limit on all vehicles including caravans is 3.7m.
Good info, thanks!
I noticed though:
"or the length of the front load carrying area/body ahead of the rear overhang line in the axle group, whichever is the lesser ... Front load carrying area is the distance from the centre of the axle/axle group to the front of a load carrying or the body (whichever is longer). Areas ahead of the body that can hold load are items like toolboxes, gas bottles etc."
Or our van, counting the pole box, that would drop the overhang to only ~3.2. Mind you, even with bag on the spare out the back, it's only 2.7 so I couldn't really imagine another 1/2m back out there!
Another thing to keep in mind though.