Run a an HDEO in it and change it once a year.
It doesn't do a bit of good to start it unless you plan on driving it long enough to get all the fluids thoroughly warmed up.
I would be more Concerned about keeping the tires out of sunlight and the battery charged for when you"need" the 4x4. In fact you could make a year on any Properly rated motor oil at this mileage as long as you get it good and warm when you start it.
Living where you live I would be using it as a Toy more often on some of the scenic trails you have.