Hey Doug,
I insulated my entire trailer and finished the ceiling and walls using 1/4" ply. I removed all the luan ply on the side walls and got down to a bare trailer. I then placed 1" styro in all the walls and ceiling using foam safe adhesive. I cut wiring channels and wiring boxes in the styro to support my 110 and 12 volt outlets. Ran all the wiring and then sheeted everything with 1/4" ply using 1" self drilling screws into the trailer frame. You are correct that you can not make the bends in the corners on the ceiling or wall. Sheet the entire trailer as close as you can to the corners.
I ripped some 1/4" ply to bridge between the wall and ceiling, roughly 12" wide. I took those bridge pieces and stapled them to the wall and ceiling and then used thin strips to finish off the joint so it looked nice.
I'll get you some pictures this weekend to help you visualize what I did.
My trailer sits out and I wanted it insulated from the heat. I took the vent in the ceiling and replaced it with a 12volt RV fan driven by a thermostat set at 95 degrees. When the trailer gets 95 inside the fan comes on. I've got six vents in the floor that draw the air from under the trailer out through the roof vent.
The power is provided via a large deep cycle battery which is fed by a 45 watt solar panel mounted on the top of the trailer. I never have to plug in to any kind of power, its all self contained. The 110 outlets are powered by a 800 watt inverter via a swich on the wall. The trailer also has interior lighting and 12 volt power for battery chargers.
Lesson learned are that I have never used the 110. The inverter sucks the life out of the battery in pretty short order (within two days). The deep cycle battery is not a good choice if you have large battery chargers to charge your lipo's. I've started flying some larger electrics using 8s packs that charge at 10 amps. A deep cycle battery is not made for high discharge so when I have two chargers running the battery gets below 11 volts due to the amp load. If I use a car battery I don't have that problem because they are made for a higher discharge rate.
I'll post you some pictures this weekend. Good luck, its a fun project and well worth the effort when completed. Jerry