I had an 05 plate 2.8crd auto, and the oil filter was very vulnerable. I fitted an ASFIR aluminium skid plate, which also protected the auto box and transfer case. I didn't lift mine since it was my daily driver, but it was too low for serious offroading (but great on road). I know when I sold the skid plate, and had a few battle scars (so it did it's job). I took mine laning to Spain a few times.
I seem to recall that 2" suspension lift is the way to go, either cheap spacers or better replacement shocks/springs. Heavy duty springs are required due to the extra weight of the diesel engine.
As mentioned, LOST is a good place for help, and I seem to remember a Dutch guy called Tony, living in Spain, would give some good advice for modding the diesel models, since most kits available in the USA were for the petrol versions (but it's been a few years since I checked).