I have a Champion generator I use to run a Jugs pitching machine... works great... affordable... but you also have to deal with the noise it throws off.
Honda or yamaha inverter is what you want 1000 or 2000i if you want extra power. You can still talk standing next to them and your neighbors will like you more. Otherwise any will work. I have a Coleman 1100 that runs my fan and lights when needed. But it's noisy.
Honda is a great choice and they are very quite, but they are expensive. Figure out your maximum wattage requirement and use a properly sized generator.
Noise is the big issue. There is a good article in consumer report about ratings. It would appear gas beats out propane when it comes to how long it will run. Best deal is go to an auction. You can get one that is almost new that someone bought and never used it. I bid $200 on a $1,400 generator that had been used once.
I have used a converter on the old pickup truck to run 2 industrial fans and a pitching machine. If you are not familiar with a converter it converts 12V to 120V.
The only thing is the pickup has to be running and it has to be close enough to the field to reach with an extension cord, but works good.