my 0. 02-
This question comes up on the volkswagen diesel forum, as well. (google fred's tdi page)
imho: since it's "only" a year, and since you possibly have someone willing to start the engine, I would be inclined to recommend keep the fuel tank full (to avoid condensation forming on the inside free volume), and keep a trickle charger on it if possible, and have the engine started every 3 weeks to a month. If the vehicle will remain "on the road" (ie. licensed and insured) and the friendly helper is capable of driving it, then I'd say also good to take it on an errand once a month or so (but not in winter salt- just let it sit during the coldest weather). Mix some diesel juice in the fuel tank if you want to, but I think it will survive reasonably well. Cold weather slows the rate at which fuel degrades, and everything I've read suggests that diesel fuel deteriorates at a slower rate than gasoline anyway. Preferably clean it before storing, and don't do anything such as wrap in plastic or tarp etc, as that just traps moisture. That's my 0. 02.