Hi,
You and the wife are doing great!
For the power converter removal, if you haven't reached that point yet, remove one wire at a time, marking each with a number and noting the terminal from which it was removed. Take lots of pics of the wiring and wire terminals "before" you remove them.
You mentioned wanting to try doing the back wall, etc., from the inside without removing the siding. Not sure how far you have made it. The tear-out is one thing; since the whole area is gone, I don't recommend rebuilding the area from the inside only and not taking the siding off.
Now, why do I say this? The metal siding contributes to the structural stability and rigidity of the rear wall. The siding is stapled on from the outside, hiding all the staples with the lap joint of the sheet above it. The corner, between the side wall and the rear wall stud, is critical that the siding is stapled to the new wood from the outside. Think about this: how are you going to attach all the siding to all the new wall studs from only the inside? If you have found some ingenious way of doing this, please share your approach.
I know this is a lot of work, and you are doing great work too. When you reach the finish line, you'll have done a good job. And lots of campfire stores for years to come.
Thanks for sharing,
John