Sounds like the same setup I had on my ORV. My controller was a 30 amp PWM. If your panel is getting good sun (no roof) you should be good.
The kill switch may not disconnect everything, but your panel should take care of anything that is not shut off.
In my current rig I still had a draw of about 0.05 amps with the switch off. I never could find the culprit.
Get a Victron BMV-712 and set the current threshold to 0.01 or 0.0 amps to see what actually happens.
2018 F350 Limited, 2021 Arctic Fox 27-5L
300 Ah Battleborn LiFePo4, 3kw Victron Multiplus, 600W Solar, SeeLevel