You might want to incorporate considerable vibration and noise suppression insulation into the fridge cabinet.
I had that same fridge, though labelled a Norcold. Same thing though. Same Sawafuji compressor.
I battled noise and vibrations until the day it died(~ 5 years running 11 months a year). Mine was basically floating inside the extra insulated cabinet at the end, but still, It annoyed me greatly. I'd even removed the cooling unit and isolated it from the fridge box.
I made great reductions in both noise and vibration, but it would still make falling asleep more difficult. It would also develop these harmonics which would start things buzzing in different parts of the van. Overwhelmingly irritating.
Don't just think you can put the 4 screws into it to hold it in place, it will rattle the whole Van.
When I first installed it in the cabinet I built around it, it was audible from 15 feet outside the Van, and I could confirm the compressor was running by touching the body.
I now have a Vitrifrigo with a danfoss/secop compressor. 1/3 the noise, no discernible vibration, and more efficient to boot.