is your house
battery going to be inside or outside? If inside then adding a built in port for plugging in a portable
solar panel is a good idea. The best time to install any thru the wall ports is before you insulate. That way you can add blocking on the inside where they go so that the mounting screws have some wood in the interior to thread into. So be sure you think carefully about what modern devices you or future potential owners will consider to be nice to have features.
It is nice to have a 12v outlet on the exterior, near the exit door; use a marine version with a water tight cover over the socket. You can use that with a USB adapter, for 12v air compressor, a string of 12v exterior
lights, 12v portable table fan, a radio, tablet, phone charger, bug zapper, etc. Remember that area usually functions as an outdoor living room. The plug-in socket allows you to keep the screens closed without having a cord threaded out a window or the door.
You might want to add a port somewhere on the side or roof for installing a cable to a radio, cell phone or TV antenna.
If you are going to have
solar panels on the roof the time to get that external port installed is before you insulate. It is also the time to install blocking on the interior side of the roof so you can screw the mounting brackets for
solar into those blocks for extra security.
In my trailer I bonded some plywood plates to the underside of the roof to mount my interior overhead and wall
lights to.
I have a trailer that needs a support pole that starts at the countertop and helps support the ceiling so I also put in blocking against the ceiling for that function.
Just think it all through carefully before you put in any insulation, now is the easy time to get your blocking in. Also be sure to take photos of the blocking, print the photos out and add in some dimensions showing the distance to the blocking from a known, fixed point such as the edge of a window frame, door, the floor, etc. You can even add in some blocking for some future application you might want to add a few years from now. For instance I put in a plywood plate to support some fuel canisters I might want to add to the front or rear of the trailer should I decide to be off grid and need extra gas for a
generator. I don't know for sure if I will need them but if I do I am ready to bolt them right in knowing that they will be well supported.