Sure if you are doing a day hike then one body and a few lenses is fine especially if you have been to the area multiple times and know what lenses to bring. Always a tripod for landscape work. But there is more in the vehicle.
One of my biggest things is secure storage and easy access, the shot you always hate yourself for not getting is the one where you couldn't access your gear in time.
I am getting a vehicle built up for me in the States now. And it isn't a ridiculous price or build like a lot of the vehicles here. Minimalist is my goal. No roof top tent, no fridge, no fancy dual burner propane camp stove, no no no. What I bring a backpacking style kit, ground tent makes a way better base camp than setting up a roof top tent and taking it down in the dark as that is when I leave or return from camp, just leave it on the ground...
What is it? A Jeep Scrambler with half cab (also have Alaskan Postal Top but probably going to sell it now). What is happening to it? Well it started off as a reliable build from the previous owner, new rebuilt I6 engine with howell fuel injection, lots of other reliability and improvements also. Going to keep the half cab shell and install a land rover type safari second layer roof with vents to keep it cooler in the desert since I don't want AC. Seat brackets will be removed and seats will mount on what is basically two locking safes. Center console is gone and will see a custom molded foam trough with cam buckles to latch my 600mm or 400mm lens. Custom canvas seat covers with basically large nalgene sized water bottle holders for storing lenses. Also on the covers will be the military style loop webbing stuff which a lot of my pouches use to attach to my backpacks (filters, lenses, spare bodies, etc). edit: MOLLE that is what it is called... Dual batteries and pure sine wave inverter. Rip off roll bar and install a custom aluminum tonneau cover the locks securely. Inside bed is where my camping equipment, water, extra fuel, and pelican cases go. Cover plenty strong enough to stand on if needed. Adding a 40gal fuel tank. Then just some basic fix ups any 30yr old truck also needs. Roll cage inside the cab. The whole thing will look quite inconspicuous when it is done (no fancy boxes outside, no tent, no jack showing, no fancy bumpers, no stickers, no electronics showing inside the truck with everything locked away, ...).
Basically to sum it up easy access to equipment, secure storage for equipment, inconspicuous, reliable, electrical power. That is what you need for extended duration wilderness photography from a vehicle platform. Comfort is gone as there is no room for it and it enhances the bling way to much. Who said I can't eat mac and cheese and beef jerky for 3weeks straight living on the ground? And why do I need a shower, I am not traveling with anyone. Mine is going to come in around $25k all finished, maybe 30k max. The price of a new Tacoma with nothing added on; while I have a new drive train and it is built up the way I want it just on a minimalist old body... We traveled for years without these fancy gizmos, why must a sacrifice storage and weight for them now?
Could I have done it cheaper, sure. But I love the CJ-8 platform and it gives me great off road performance.
