Joseph,
I am currently researching the issue of army supply wagons as well. I have gathered some information which may be of help to you. The standard wagon bed was about 10 feet long. This does not include the draw bar or horse teams. Without exact measurements I am currently assuming that a four horse team would take a further 20 feet plus any interval between wagons. Hope this helps a bit. If you have any information on the wagon itself I would be grateful.
Regards,
Alan.