[elhigh]

DonE has left us a few questions, but has given us some important info:

You're nowhere close to a paved road: vehicle failure in the middle of your driveway leaves you walking either 1.5m to the road or 1.5m back to the house. In very inclement weather, this could be fatal.

We don't know if you ever tow anything. Referring again to the miles of unimproved road, I couldn't in good conscience recommend narrow tires.

Is yours a belt-driven fan? Swap out to an electric. If nothing else, the engine warms up faster and it actually frees up a bit of space in the engine bay.

Looking at Smoky's suggestions above, I second all of them except the tires and the final drive changes - hold off on that until the weather is nice and you've got plenty of warm weather in which to shake it down - let any stranding failures happen when you're not likely to freeze to death walking home.

Regardless of Smoky's opinion, consider adding a tonneau or a smoothie bed cap. Mine makes a big difference, and it's possible that those differences experienced are truck-dependent, so one particular conformation of vehicle may get benefits while another doesn't. Aerodynamics can be subtle.