Could you say where you found the flex connector that fits into the Burley hitch? I think I found most of the other parts you've used.
http://www.northerntool.com/shop/too...7395_200497395
http://www.northerntool.com/shop/too...ct_13794_13794
http://www.amazon.com/dp/B0038LPOD6
I'm very interested in this project, because I like the idea of the Travoy but not the expense. Do you have bags that you use with this, or do you just haul boxes?