Found my book, but it's the other one that I was thinking of (which, of coarse, is in TN while I am in NC!). Pick up an issue of Mother Earth News (or look at it in the library). They have lots of ads for heating products that are geared to the solar folks (efficent and economical). You might find a low enery one there.
Do you have a Webasto heater on your skoolie? If so, you can use it to build a heater. Look at the parts manual (.PDF) at www.hydro-hot.com
for either the aqua-hot (40 ft RV's) or hydro-hot (35 ft RV's). They run about $6K+ but they are simple units. We had ordered info from the copmpany and recieved a complete parts list (high mark-up). Broken-down, we figured we could build one for less than half and that was buying most of the parts thru Lowe's. Our shell only cost $5K and I refuse to put in a heating system that costs more that the bus shell or my car.
I have hear that Espar & Proheat uses the Webasto type setup (like Aqua Hot) but Hurricane http://itrheat.com/marine_home.html
uses "off-the-shelf parts which makes it easier to fix if/when it breaks down. it is a diesel unit.
As far as I now, all diesel heating units and gensets can use home heating fuel, kerosine, "off-road" diesel. The cheapest way would be for you to get a tank for home delivery and siphon from the tank into your bus' heater fuel tank. The Webasto based units can heat your water, pre-heat your engine (great it you have a diesel like we do) along with heating your space.
I keep looking at the Webasto type unit (I can buy a Webasto thru ronthebusnut among other places) and just keep coming back to it even though we look at other heat systems. I like LP heat and will use a tankless LP water heater. But David keeps talking Diesel genset and we have the space available to install a large fuel tank, where we removed the old over-the-road heat/air unit and we kept the two 12vdc blower units that we can use... I have an idea to make a long heat exchanger in the bays and just run small flexible ducts off of it using the 12vdc blowers. I also have several of the 100# LP tanks that I can use as a water tank to wrap copper pipe around (then insulate)and heat my water. But this is your conversion and you are the one who knows what you need and what you can put in.
The upside of building it your self is that when it breaks down in the middle of the night, you can fix it your self (if you have the parts). The downside is that it is a lot of research and you would need to look at several different methods of heat extraction to figure out how you can make it work for you. I have found most of my ideas come from the methods used in home-brewed solar projects.