This may sound excessive, but its good to know:
If you need more power, you can put a boat battery with a bigger power inverter in the trunk of the car. These can go up to 3000 watts. Its expensive, but a gem to own. If you need this, get someone who knows how to do it to rig it properly. There are marine inverters too, with salt/air/water protection. Then, you can rig lights inside or outside the car without a camera insert/process trailer.