I have similar issues:
- Towing several tons (travel trailer or 23 foot trailerable-with-extreme-trailer deep-keel coastal-water-ocean-capable sailboat) up and down mountains and cross-country.
- Going to/from the ranch - over 250 miles one way (over the Altamont grade, across the central valley, and through a pass in the Sierras) - with the last 0.7 miles sometimes hubcap-deep mud.
- Carrying ranch groceries for several months and/or other supplies or equipment from the nearest supermarket etc. - 27 miles away.
and so on.
- Off-roading to visit ghost towns and other historic sites in the Nevada Desert - where "running out of gas" - in the absence of cell phone service - might mean your skeletons are discovered in a couple years.
On the other hand, for trips about 3/4 of the year and NOT towing, a plug-in hybrid or an all-electric vehicle with sufficient range, serious regenerative braking, and adequate cargo capacity for two week's groceries and luggage for two, would be ideal. Charge it up at each end (off a windmill/solar at the Nevada end) to start full, use regenerative braking on the downslopes to power across the valley or up the next up slope. For a hybrid: Top off the batteries while cruising the central valley and use batteries plus engine to avoid being a creeping traffic hazard on the mountain roads.
My cycle would be almost identical to a Silicon Valley worker who mostly commutes 25 miles each way and occasionally vacations at the Lake Tahoe ski resorts or Reno or camps in the Sierras. A single vehicle that could do both - rather than needing two vehicles to accommodate the use pattern - would be ideal.