[EricH]

Second idea for solution:

Because teams are bringing their own robots, have all the teams on a given "route" (e.g., North, South, West, Northeast, etc) to each event go in on a U-haul or trailer. The farthest team rents the trailer and is reimbursed by the others, depending on how many teams. (Or, if the trailer is owned by a team/individual, gas reimbursement.) As the team travels towards the venue, the trailer stops at the other robot locations to pick up the other robots. Use a spreadsheet or something to determine who is on which "route" and contact information.