Like you I was not sure where to install so finally mounted mine under front deck platform close to graph and put a battery disconnect switch on front deck also to kill the power when moving, no environmental issues so far but it is protected from direct rain and does get descent ventilation. Would suggest to install the box where you can see the LED status light for blink codes.

Mine may not be installed in the correct place but been installed two years now with no issues. I aired on the side of caution because of the cost of the unit, repair or potential warranty claim.