hehe, extension cord
The generator isn't a bad idea... but it would be fairly loud, and how to turn it on/off? I'd bet is is for "camping", although what's the point of camping if you have A/C?.
A power inverter that big would be very expensive, especially if it's for using a cheaper A/C method (a 600W is about $60, and from there they get expensive quick.
What I'd do is get a DC motor, and replace the motor for the compressor with that. Then, hook a relay up to the compressor controller. You'd probably have to get a ford starter solenoid for a draw that big, not too expensive. Definately use big wire, I'd use at least 4 guage, but figure out the amps of the motor and use wire approved for that many amps.