"And if I ran it almost dry, I could conceivably get over 800 miles per tank! Nifty! "
congrats on your purchase and the mileage. just a friendly word of advice though, with any diesel, do Not run the tank dry or near to. you will be sorry. it churns up all sorts of nasty stuff in the bottom of the tank , clogging fuel filters etc.
if you can try to fill when it reaches less than 1/4 tank especially in cold weather.
good luck ! sounds like a great ride