Didgiman-
Welcome and congrats on new trailer... I agree with Tarheel that trying to adapt tow vehicle to antique and discontinued connector is bad idea... No matter how much you might want to maintain the 60's ambiance and feel of your trailer, spending $$ to replicate 40 year old electrical technology is bad idea... Make sure batteries, power supply and charging system are current (sic) technology...
As for the other 999,999 questions you referred to, as a New Member your second official assignment (after posting "Hello" message as you have done..) is to learn to use the "Search" tab in blue bar above... Clever use of search terms and searching strategies will take you neatly through the tens of thousands of messags and lessons already recorded here..
Good luck!
John McG