Great information - thanks for sharing and telling us about this product.
It is so, so important to get a full sheet of plywood out to the perimeter in order to give a good bedding platform for the "C" channel to be able to do it's job of holding the shell to the frame.
"do it right the first time"
Hope you get as much enjoyment and use out of your '72 as Mary and I have with our '78. It's been 10 years since we purchased the Sovereign
, but we now have, for all practical purposes, a new trailer built to "our" specifications and laid out and furnished exactly as we want.
How about some step by step pictures of your project?