I have a suggestion for a cart. When we attended 2 years ago, we didn't want to take our big/heavy cart. We went to Harbor Freight and picked up a fairly cheap cart and used it for the event - it worked very well, was light, and folded up nicely.
There is a store in St Louis:
4610 Chippewa St Ste A, St. Louis, MO 63116
Item is:
http://www.harborfreight.com/materia...uck-68894.html
It's probably easier and cheaper then trying to build one on site.