On the interior, you will need to remove all of the lower interior skins to give you access to the U-channel at the bottom of the wall. You will also need to remove the interior wheel well covers. Once this is done, you will see that the exterior wheel wells are installed under the subfloor (so they stay with the floor/frame), but they are riveted to the shell. These rivets need to be drilled out as well. There will be bolts and screws that connect the U-channel to the floor and to the outriggers. Remove/break all these off.
There will also be a "hold down plate" in the front, and probably in the back as well. This plate is attached to the frame, and is riveted to the shell with a double row of horizontal rivets. These need to be drilled out.
I believe that on the 60's vintage trailers, the U channel at the bottom of the wall rests on the floor, but does not wrap around the floor (like on the 70's era). Confirm this, and if the channel is just resting on the floor, then there is no need to separate it from the shell (in fact you will be making a lot of work for youself if you do).
You will also need to remove the celing assembly for your AC so that your ceiling is flat. That way, you can run a beam from front to back and hoist against it, distributing the pull across the length of the roof. Pad the beam so that you don't damage your interior skins with rubbing/scratching.