Our mobile setup is either with a power generator or a boat battery. Both solutions are capable to run strong projectors with e.g. 7k Ansi Lumens. However, you still need some kind of logistic, since generators and batteries are heavy. So it's not that super mobile like Benjamin's setup.
We have a Honda generator with 1k watts:
It's rather expensive, but therefore small and quiet.
For the boat battery you need a power converter, e.g. this:
With the generator and the battery you have to take care, that the power supply is constant, as a changing power level can damage the projector.