You leave it on LP while in storage.
Mine is always cold even when the frost is melted from fins during defrost period. Most items are cool during defrost. I have mine plug in 110v and do check it at times just to make sure things remain cool. I park MH pulled in drive or backed in slite sloop in drive but refer works the same either way.
The days have been warm lately and cooling fans up top of coils have been cycling off and on. More so if sun is hitting side of refer wall.
The door surfaces of refer will get hot when its really hot and coach is closed up, some of this heat may radiate into the box area causing temp to raise. Freezers always have frost.