Sounding good, but I'd suggest that 8mm2 may be a bit light unless the fridge is pretty close to the battery. I would use a minimum of 8AWG which is 10mm2. Also if you are expecting cable induced voltage drop when you have the compressor running, do you have the compressor & fridge on the same circuit? If so I would advise a separate circuit for each.

I have just run two new circuits in our truck. One just for Starlink running direct of 12v (12v to 47v converter) from a circuit breaker rated at 16 amps, & the other to run an Engel freezer & my Cpap machine from a 10 amp circuit breaker. Both using 8AWG/8B&S cable.

I'm kinda hoping that you have used the same gauge cable & wrongly assumed it is 8mm2?