Almost an impossible quest.

Most “resistant” vehicles are going to be 40+ years old.
Spare parts, Napa, Auto Zone, etc.

Best option, find an old vehicle that fits your needs and take a class through your local community college on service, restoration and such.
Do a complete frame off restoration, that way it all gets done, you now know it inside and out, and you increase both it’s and your value.

Option two, no space,no skill.
Talk to your local high school,see if they need a project, and let them restore an old one.

The old military ‘Dodge’ Power Wagons are out there, same for the ambulances. Think 1950’s MASH style.

Next option, depends on your location.
The ‘sandrails’ built using tubular frames.
Generally an old VW engine, but built to beat up.
Add some amenities such as sheet metal external panels and such, there’s nothing to go wrong as long as you have a pre electronic ignition system. Except for the condenser coil and such.

I seem to recall a decent article on this in an old ASG magazine. Will dig it up for you.