Thanks for the advice everyone. I'm abandoning the partnership idea completely. When I talk to him again I will inquire about leasing his equipment and taking over all hot food sales with my own insurance as well as a payroll deal with some type of commission.
One thing I have going for me is that the unit is mounted through the back wall of the building. I think the only reason that he hasn't sold it may be because he would need to get more than its worth to cover the cost of filling in the huge hole that would be left.