Hi there, Zenman, and welcome to Airforums.com
Best of luck with your new project, and we look forward to following your progress. As Dan pointed out, hanging heavy things off the back is a definite no-no.
In fact, if you have the rear bathroom (or as AS calls it the "full" bathroom) model, you very likely already have problems with what is called "frame separation" and "rear sag". Use the Google line of the Search function up top in the blue bar to look up those issues.
Curious about your goal: do you intend to keep the trailer in towable condition, and take it to the projects you will record, or is it going to be stationary?
Also, why an Airstream? Wouldn't an SOB (square old box) have given you more space for less money? Especially when you will be adding air ducts and running all kinds of wire around. I would have thought that the corners would be a natural spot for that stuff.
Anyway, please take the time to start of with some photos of your rig, so we can see your "before" condition? We love photos...