The PVC sounds like a good idea for some of these.
The ones I have done in the past we try to keep as much outside the cooler box as possible.
Inside depending on job specs I have used RMC, EMT, compression fittings, set screw fittings, LFMC, FMC, WP boxes, normal boxes.
All are NEC compliant IMO.
One important note, always seal the raceway where it passes from inside to outside the cooler. If you do not seal you will very likely have call backs for rotted out devices, fixtures etc. Besides, 300.7(A) requires it.