Over the years I've modified a couple of trailers for carrying Hobie's stacked vertically.
Chekika's link (thanks Keith) shows a pic of the latest version for a TI +AI. Before that it looked like this:
It is based on a cheap Carlex Easytrailer 880GA tinnie trailer. I added the framework (50mm) RHS and rear extension (100mm RHS ripped diagonally). The framework is bolted to the Easytrailer and can be removed by undoing 2 U-bolts and 2 rear bolts. This framework was on an earlier trailer (viewtopic.php?f=73&t=11063
) but if I was building from scratch the lower 50mm RHS would be in one length that would cantilever for the rear extension. This extension assisted in loading the top AI.
Here is a link to a dolly cart cradle but it is for a TI:viewtopic.php?f=73&t=40346