Go to advanced search and type in Armstrong Bay Breeze and search within Air Conditioners.....you will find just about everything you want to know about the old Bay Breezes.
I have the same trailer as you and was going to scrap mine and put a new one on but have since decided to restore mine. I am glad I made the decision because it will keep the integrity of the original design of the trailer.
There is one particular post that shows how to cut the hole and repair your roof. You may want to check with a refrigeration person before cutting the tubes just to be sure you are not dealing with freon in any way.