Trailer Hitch / Tarp Pole

OK, I think I've got the hitch/pole figured out. Imagine a telescoping pole with three sailboat halyards installed inside.

Of note:
-it extends from 1.5m (hitch mode) to 2.5m (max tarp mode) in 10cm increments
-it rotates on one axis at the cart end and on three axes at the bike end, eliminating the jacknife feature of the first prototype (thanks Adrian!)
-in hitch mode, the hook can be tightened down, eliminating the rattle feature of the first prototype. the new design also eliminates the pin that held the hook in place, which was both awkward and sketchy.
-the rope is 1/4" braided nylon - strong enough to hold a large sailboat sail up.
-aluminum would be ideal, and hopefully not too expensive.
-each cart would need a 100mm x 100mm x 5mm plate installed in front of the rotating wheel pivot, and on top wherever poles might go.
-in pole mode, there are three equalized ropes - one for the tarp (with a hook that can accommodate several grommets when the tarp is folded) and two to attach to the ground (a block, a fence, a stake)

Whaddya think?