Thanks for the advice. The more I read the less I know about generators. I think that if I had a diesel motorhome, I'd buy a diesel genset but then I'm probably missing something there too.
The Conversion kit idea might just be the answer although it adds a couple of hundred to the price of the genset.
I guess that what I really want is the impossible. 50lbs, 5000 watts and runs an hour per pound of propane ... oh yeah and costs under $1000... just ain't happenin'.
While the btus per gallon of propane is less than gasoline ... depending on the data source ... 92-95,000 btus per gallon of propane vs 110-120 btus per gallon of gasoline, engines are more efficient on propane and pollute less.
Still a 10hp gas engine vs a 10 hp propane engine produces the same 'lectric output. The difference will be the cost of fuel which as near as I can tell is about break even.
Also while we're on the subject, why does a 'Sportsman' 4000 watt genset cost $900 and a Honda or Yamaha Equivalent cost $4000? I know I want a quality generator but the price difference seems extreme.