How much more fuel efficient do you think a diesel generator will be compared to an off the shelf gas generator from honda for example? It seems like a lot of work for not much gain. Usually gas generators that are run at constant speed and max load are darn near as efficient as a diesel. Don't take it the wrong way, I think you have an excellent concept in mind. I just think an off the shelf generator is worth a second look. I'm sure you've already done that. I don't know if 6.7hp is large enough but it seems to be the most bang for the buck and weight. They go all the way up to 14.7hp
http://www.hondapowerequipment.com/M...delName=eg5000
Used generators are dirt cheap on Craigslist.
cheers
Justin