Hmm good question. I have a 68 Tradewind, the electrical system is (mostly) ok. I wonder though about whether the trailer has aluminum wiring inside (I believe that was common back in the old days) as opposed to copper. From what I've seen most of the wiring I can access seems to be copper in my trailer. Copper is decent. You would only need to worry if you suspected that it had ever overheated, possibly been hit by lightning, etc. With the skin on the trailer aluminum, and that being a good conductor, if you had a bad short it could be really hazardous.