Anyone tried to hook up an alternator driven by the engine either directly or via a power take off?
That's way too much engine for the task. Instead of near 1/2gph, you'd be running at double that, and stressing your cooling system too.
Someone else posted on propane availability. For me it was both the higher cost and lower availability. Ignoring generator acquisition cost (where gas is cheapest, then propane and then diesel), there's fuel-per-KW... where I think diesel is cheapest, then gas, then propane. The same Onan engine/generator puts out 2.8KW in gas and 2.5KW in more expensive propane. I can and do refill gas all the time. We seldom refill propane. While we have a water heater, stove and furnace, we seldom use them. We use the microwave a lot more than the stove, and the AC/heater far more than the furnace. Only the fridge gets any real propane use (though it can run AC also), but that really just means one or two fills per year. Can you tell it's usually hot wherever we go?
I hope gasoline generators don't go the way of the dodo. Where I live, it is a PITA to find anyone refilling propane, especially somewhere RV friendly. I'd probably end up using an Extend-A-Stay system, a luggage rack for the back and some 20# bottles.
I'd like to see Onan make a tri-fuel generator with materials good enough to take E85's corrosive effects. That way, the generator can run from the main fuel tank in winter (saving the propane for the furnace), and in the summer when the propane isn't in use, use that for the generator.