Howdy,
You can have a large propane tank onsite. A 100 is the largest transportable (DOT Standards) that is allowed. The same thing goes for a Diesel Transfer tank in a Pickup truck (DOT standards says 109 gallons) If you have a propane genset, and only have a 100 gallon tank, you would need to disconnect it, drive somewhere, re-fill it and drive home. Most of the time when you need to run the generator, the roads might be impassible with trees and lines down. A larger onsite propane tank sounds great, until it runs out and the big propane delivery truck can not get to you.
Farm= tractor, and diesel. The diesel genset might cost more, but the same thing could be said about a diesel tractor. Cost more, but runs a long time.
Tip*
You said you have a 1hp pump sitting at 600ft. You will need at least a 6kw genset to crank that pump. A little honda 3000i will not do it.
Things to think about
Diesel generator= liquid cooled running at 1800rpm is the way to go. Yes, air cooled is cheaper, so is a genset running at 3600rpm.