Hello, I have it under the bed (boat) You can hear it, but the cooler is louder when it starts up. VG

I have just tested the following with my Anker Solix: 92 watt AC load: fan does not move. It has been running for 20 minutes now and the fan still doesn't move.
It is currently 24 degrees in the room, but I don't know how the fan behaves when it gets over 30 degrees in your bus or what the situation is when you have 60 watts for 12 hours and then the part heats up a little.
In my experience, the fan only switches on at around 120 watts, but even then it is very quiet. Even at full load, this part is not really loud.
If your cooler is operated with direct current (12 V car socket) then the heat development should be even lower than the same load with alternating current (as I am currently testing), as an inverter still has to be operated...
Hope that helps.