We used an old Chevy truck. Jack the rear of the truck off the ground or use a winch on the rear bumper to suspend it from a tree branch, then, with one rear wheel locked in place and the other rear wheel running a steel wheel with no tire, remove the bed and you have a great PTO.

Tie the generator to a large tree with a rope and a block and tackle, put another bare steel wheel on the end of it by cutting off an axle to mount the wheel on, coupling the axle to the generator with a spider type coupling (We used an old Mercedes flex disc! Nothing but the best!) Hook them together with a canvas belt with a twist so one side does not do all the work and then tell everyone to stand clear or suffer the results.

You could also just use a gas engine to run the generator, but we had the old truck and didn't want to buy a stationary engine.

That and we had some time on our hands. I think a lot of booze was also involved.