Just built a setup like this myself.
35 hp Yanmar, with a clutch for side load + warm the engine up before engaging the pumps. Also allows me to start the engine without starting the pumps which is easier on the starter. 270 amp marine alternator off the crank on the front, so if the engine is running the alternator is producing. Alternator allows me to run the engine at low rpm's and still be able to to run the 120v burner with the help on an inverter of course. Everything is plumbed so the fuel for the engine + burner is pulled and returned to the 80g side tank, so no tanks in the truck, and no jerry cans needed. I figure with the diesel and being able to lower the rpms I will pay for the difference between the gas/diesel in the first year.