Since my trailer was mentioned, I'll chime in.
My trailer was designed and built for my family of 4 which is 2 adults and 2 kids 5 and 2 years old.
The concept was, I wanted a bedroom for 4 and also use it as a living space when outside condition is not ideal. I wanted a space big enough for 4 of us to sit, eat, watch TV, etc.
Because of this I decided to make my bunk retractable so I can store it away to expand the living space.
This concept prove to be a very valuable on our maiden voyage since it was pouring down rain when we arrived at the camp site and could not set up the shelter. We cooked under the galley hatch and eat and spent whole evening and night in the cabin.
I agree with you about the permanent AC. I'm in Tennessee so if I want to do any camping during summer time, I must have an AC.
Above are some design decisions I had to make during my design. I know you have your own concept and ideas, but let me put in my 2 cents about the design you are brewing so far.
I would really look at the weight balance of your trailer if you are not going to have a galley. Looking at you sketch, it seems very tongue heavy when fully loaded. Also the way your AC is mounted, make sure to beef up the frame for it. 40lbs of weight cantilevered off the axle could put a lot of stress on the trailer frame and the walls.
Also, make sure to at lease have a concept of your electrical system figured out. That could add more weight especially if you are going to have a battery. Also it takes up more space than you think.
I threw a lot of stuff at you, but I don't mean to scare you. I just wanted to share some of my setbacks so that you don't have to go through the same things.
