The wall is only 1 inch thick and I found that the switches are deeper than that. In order to get them to fit I had to make a deeper pocket by adding the thickness of the switch plate. It is made of 3/8 inch plywood. I have a pair of switches like this near both doors. One switch turns on the porch light just above the door so if you want to get out at night you can switch the porch light on from inside before you open the door. The other switch turns on the dome lights inside the cabin. If you are getting in at night you can reach in and turn on the dome lights before you enter. These switches are located less than a foot from the door so with the door open you can easily reach in to hit the switch. They are also near the head of the bed so that you can easily turn on the dome light from under the covers while you are laying down from either side of the bed.
I wanted to show you what the wiring looks like on the outside. On the driver's side outside wall of the trailer is a waterproof shore power connection which I bought at camperworld. Near it you can see a yellow romex wire that goes over the top to feed two 110V outlets, one in the galley and the other in the cabin. From the battery you can see a red and a black pair of 8 gauge wires. They travel from the battery underneath the trailer where they enter from below through holes drilled in the framing. All of the smaller gauge black and red wires have now been tested and when I fasten in the insulating foam I will put them all into channels and give them some order. I realize that right now it kinda looks like spagetti. The amazing thing is everything worked when I powered it all up. All the outlets were live, the lights all switched like they were intended, and even the battery tender was wired right and started charging the battery as soon as I plugged in the shore power and turned on the 110V switch.