Had one on a cat, so can't advise on gimballing. The movement of a boat helps the
coolant circulation, or so I was told.
But follow manufacturers instructions completely. You need good air flow for the
cooling air. I improved the performance considerably by adding a 12v computer fan to aid in exhausting this air (I had already increased the vent area dramatically to meet the mfgs. requirement)
I was also told if performance was below par, to invert the unit for a day or so, to "burp" it. Seemed to help.
Note that (AFAIK) none of these things are really made for the
marine environment, so be prepared to fight rust.
Since the 12v
charging on this boat was an
Outboard motor, this frig was very satisfactory.