Optimal wire type for Offroading

I live in Australia and am planning on construcing my own wiring harnes for a 4wd (NIssan GQ Patrol).

These vehicles are notorious for running hot even before they are boosted, and when taken into consideration the environment this vehicle will be living in:

Would TXL still surfice (maybe with extra harnes proteciton?)

Or would Spec55/motorsport wires be more nessisary?

I'd say don't take the chances and use M22759/32 cable. It's more expensive, but considering the overall cost of building a complete harness, it's almost not relevant.

In addition, use Raychem DR25 at least for the critical areas where protection is needed.

And to go even further, there are heat protection sleeves which you can use where it's really hot.

That's what I would do. Others would do it differently maybe.