More Power
While the two Group 27s is a good start, I think with time you'll probably want more power. More battery capacity will help keep the voltage from going down so low and the batteries will last longer. The refrigeration unit really drains batteries! One thing to consider is the start-up current for motors is significant and this causes a surge in current and a corresponding drop in voltage. Rule of thumb is the starting current is about 3-1/2 times the running current and running a motor at low voltage shortens it life expectancy. To help the motor out the best thing that can be done is to provide high voltage at startup and this takes large conductors and short runs. The earlier Hunters, like our H-35 and probably your 37 came from the factory with conductors sized for the installed loads and not a whole much more. Looking at the holistic picture, upgrade all the conductors and keep the runs as short as possible. I'm putting a subpannel near the battery compartment just for motor loads: Autohelm, refrigeration, water pump, and forced air heater.With regard to compressor location, our Adler/Barbour is locaed under the port settee near the ice box. It takes air from under the ice box and water heater area and blows it out through a rectangle vent in the side of the settee. The noise is barely audible at startup and once it is running it's hardly noticable at all. Suggest listning to one that's been installed. Low voltage might make it sound noiser too. The A/B cycles a lot so if this is a problem you want to get it right.Insulation: Add more (if you can)! Check thickness with an ice pick.When you drill the hole through the wall of the ice box for the copper tubes, consider putting in some wire to run a small light. The new Hunters advertise they have a lighted boxes now so one could probably buy the light fixture and switch as a part.