13,500 A/C and "hard start" capacitors and genny's

The Onan in the "C" is not like a Yamaha or Honda... it will need to have a battery, fuel lines, and power lugs. You could do this, but dropping the genset, hooking it up to a gasoline tank, wiring it up, then undoing all that and sticking it back under the "C" is a lot of work.

I would consider a 3100 watt Champion inverter generator as another idea.