I got two trailers and they are both on/in the lower left front wall under the gooseneck.

Many of the trailers that have dressing rooms, will have the electrical panels mounted in the front part of the room, on the bulkhead or side walls. Many trailers that are equipped with LQs will often have their power cords near to their electrical distribution equipment, which is usually located towards the central living areas. The LQ cords are usually contained in a closed space for storage, which can be against the bulkhead or the outside walls underneath the cabinets.

Any holes in the forward bulkhead are subject to moisture intrusion, thrown by the towing vehicles' tires, and air penetration, when ever the trailer is being towed. Some of this is lessened with a side mounting area. The wiring port is typically fitted with a closeable cover plate, that adds a finished appearance.

Gard

I installed my inlet ports under the GN high on the bulkhead wall.  The inlet has a spring loaded cover with a gasket.  This cover protects against road spray & dirt during travel.  The location under the GN protects the inlet from weather when the cord is plugged in, and the cover is open. 

I never liked the inlets on the side because of the weather exposure or large, vulnerable, ugly weather  cord covers when at camp.