Thanks! The video is great, and very similar to what I was considering. I am not opposed to to two wheel trailers, but I don't see them working with the seat post unless a super zany hitch is made.

My immediate goal is to be able to cart a box of diapers, wipes, a couple gallons of milk and random groceries. I figure if they can pull kids on a trailer bike, I can gear down and get groceries. I am actually thinking of enveloping the wheel a bit more, the downside would be road crud on the purchases I suppose.