As far as I can tell, the door is insulated and the window is dual pane, as is the small window in the bathroom. The door is something they purchase from an outside supplier.
There is a hose connection on the outside curbside rear corner for winterization. You connect a short hose from there to your antifreeze jug, turn some bypass valves inside, and run the pump to suck the antifreeze into the system. Interestingly, this same system can be used to fill the water tank from a fresh water tote as well. The Oliver doesn't have a gravity fill port.
On the streetside rear of the trailer, there are two hose connections - one for the city water and one for the fresh water fill. These need to be pressurized - simply connect your hose from the spigot to one of these two ports.
Every Oliver comes standard with the dual panes, good insulation, winterization system, piping and tanks inside the hull with ducted heat. There is no extra arctic package officially from them yet. On my trailer, since my expected conditions are so extreme, we are prototyping a few extra features to see if they make any sense to offer as additional options. I have my doubts whether any of them are really necessary, or worth the money, but I've agreed to keep them under wraps for the time being.
Oh, and the Oliver is just a light
up sign. It's constant with the running lights
, and not a brake light