Hello idahoair. It sounds like you are doing a significant upgrade to your vintage trailer. Airstream was a pioneer in the "univolt" system where ALL the appliances and lights ran on 12v
. This allowed you to be boondocking in the heart of Africa while running the comforts in your trailer off the batteries.
Your trailer has three distinct electrical systems. 1. Exterior lights and brakes and a battery charge line all powered by your tow vehicle when you hook up to tow. 2. The 12v system which is basically everything in your trailer except the AC. A key component in the 12v system is the converter that converts 115v AC to 12v DC. This allows you to charge the battery and use your 12v system while plugged into "shore power". 3. The 115v AC system mainly is the household outlets mounted in the walls plus a line for the AC. The AC system is mostly a 30 amp system providing about 3000 watts of AC power to the trailer. The AC will pull about 1800 of those watts when it is running. Plug in a 1500
watt hair dryer and you might pop the circuit breaker.
Surge protection helps protect your sensitive 115v electronic gear from voltage spikes from the grid. I don't use one, but there are just a lot of people who do. A lightning strike at your house is likely to ruin your computer, TV, stereo, and other electronic circuit boards.
The main "indicator" you might like is a battery voltage readout. Then you know when your batteries are fully charged, and when they are not.
So things for you to consider:
Find a good converter. It is the heart of your system. There are many on the market.
Consider a new AC "breaker box". New breakers may be more reliable. Upgrade one of your circuits to ground fault interrupter, or GFI. These breakers are very sensitive to voltage leakage to ground. They prevent shocks if the ground circuit gets compromised. The outlets in the bathroom, kitchen, and outside the trailer ought to be GFI protected.
Consider upgrading your 12v fuse panel.
Consider two 6 volt "golf cart" batteries and a solar panel if you plan on a lot of boondocking. The solar panel will keep the batteries charged on a sunny day. Two 6 volt batteries have more storage capacity than one 12v battery. Remember how quickly your car battery goes dead when you leave the lights on?
My intent is to help you with some of the basics of the Airstream electrical system. I hope it helps a little.