Generally speaking, diesels don't like short trips that much. They like to be at full operating temperature, and also like to be loaded once in a while. So all you can really do is take some highway trips once in a while to clean it out.
With both long and short trips, the number one thing you need to do is give your motor some cool down time before shutting it off. This is primarily in the interest of turbo longevity, but also helps cool down pre-cups/head in an IDI and pistons in a DI. If you've just had the engine under significant load, give it a minute or so of idle before shutting off. If you've just been driving slow through a parking lot (coming to uvic for example), you only need to give it 15 sec to cool down. If you shut down quick after being under high load, it can shorten the life of your turbo by coking oil in the journal. Another thing, is don't drive the truck hard until it's warmed up. Hard acceleration with a cold diesel is not good.
The other thing you should do, is look for an EGR delete kit, and look at crank ventilation filters. This will keep the intake/head clean. Otherwise a ton of crud will build up in there which is not good for valves/seats. Also, change oil more often, as although you're not racking up kms, you are racking up hours. With your engine being direct injection, it does run cleaner than an old IDI like mine though... Just monitor it.
