Well, the cartbike Mk. 2 did not work as well as hoped. On the first voyage of any real distance, the left wheel got taco'd, and the forks came loose. It was tragic, so I decided to rebuild as a bicycle. The tiny wheel from the stroller was used, and the more solid fork was attached to the front of the cart. This gives the fork a negative angle but a rake of about 100 cm, where as most bicycles have it measured in millimeters. It's ugly, and it's much harder to steer, as impossible as that seems. But once it gets to speed, and it gets better, and I'm getting the hang of it. That helps too.
I'm still keeping the 2, to commemorate the earlier model. And it looks cool.