The need for a 4 wheeler or side by side has existed for over a decade when we added the remote sites (KEYV, KEYR, and more recently K238CE) which are on the top of mountains. But the need was accentuated with the move of KEYP to the top of the mountain last year. All of the roads to the mountain tops are the typical one-lane dirt and rock roads with no guardrails and large drops. The pickup truck does well for accessing the sites in summer (if dry), but for much of fall and spring and all of winter, the rain and snow makes the roads impassable, or minimally unpredictable. That is why we are putting the need out for an ATV with tracks.
KEYP is also an off-grid solar-powered site and more delicate and requiring more attention, more so in winter. Renting a vehicle is an option, but not an inexpensive option, and it's hard to schedule when we are very dependent on the weather being good, which is not forecasted well on the mountains.