A dry-fit of the fridge and insulation (2" foam). This will determine the location of the dividing wall as well as the shelf above the fridge opening.
The Nova Kool R4500 has an internal volume of 4.3 cubic feet and draws 2.2 amps at 12 volts DC.
For comparison...a compact fridge from Sears uses 315 kilowatt-hours per year, or 863 watts per day...which at 120 volts is 7.191 amp-hours.
The Nova Kool uses 2.2 amps at 12 volts DC, which is .22 amps at 120 volts AC. This means the Nova Kool would have to run continuously more than 32 hours per day to use the same electricity used by the Sears model.
On average, fridges run 25% - 35% (6 - 8.5 hours) of the day, depending on ambient external temperatures and other factors.
We opted against a propane model because of the requirement to have the vehicle within 3% of level. We also didn't want to deal with adding an exhaust vent stack.
We also considered 12vdc refrigerator models by Waeco, Norcold, SunDanzer, and Zero.