Thank you for your response, Lectrol. This will be an electric vehicle with an on-board generator, no connection between the diesel and the wheels, and the ability to go into golf cart mode.
For those questioning the size of the vehicle:
Let's see you fit multiple carseats, camping gear, and two dogs into something else. Not to mention, with the cargo capacity of this thing, I won't need my 8mpg truck to go to the store and get cement or boards or steel or tires or..............

A chance look at an article has taught me a few things, and contradicts some of what people think:
What I want to build is called a Serial Hybrid.
I'm not the first to think of this for trucks.
This is a much better thing than trying to improve the mileage of a small car, Prius or other conventional hybrid. Why?
Look at how much fuel a truck of this size would use, or even it's modern equivalent, the Ford Expedition and Chevy Suburban. Both hit around 16mpg. For comparison's sake, lets say they have a 300 mile range. That's just under 19 gallons of gas. Compare to a high mpg car, like a Corolla, getting 35mpg. It goes the same distance on 8.5 gallons. Or a conventional hybrid getting around 50mpg, which will use 6gallons.
Now let's say that, with this system, I can get 32mpg, or double the mileage I was/should be getting. Now I will go 300 miles on about 8.5 gallons. Double the mileage of anything else, you only save 4.25 gallons in the Corolla, and only 3 gallons in the Hybrid.
Given that the people who drive trucks and large SUVs will drive a truck or large SUV at a poor mileage before they would be caught anywhere near a little high MPG car or hybrid, or actually have a legitimate need for these vehicles, the fuel savings of the truck are twice to nearly three times what you would get from the other vehicles.
So there.