For the use case the OP describes, I would recommend the following:
(1) Mount on the roof rack (leave it there for the trip), wire down the A-Pillar windshield channel to the charger in the engine bay [single or dual battery setup]
(2) Transport panels inside the car (set up on ground / lay on windshield / lean up on tire / etc - flexible placement when on the campsite), wire-up a plug quick connect up front somewhere, charger in the engine bay [single or dual battery setup]
(3) Go with a Goal Zero type system - separate battery and panels - deploy flexibly.
The only thing I see that's needed to run into the cabin would be power - e.g. dedicated higher load always-on 12V for a fridge.
I'm currently using the #2 approach.