welcome to the forum!
you don't need to go home made, most 70's era airstreams were connected with a system just like you describe.
you could contact inland rv for the parts, i'm pretty sure andy would be able to connect you with the parts you need for your project. -or- any place that handles parts for semi trailers would have all the plugs, recepticles and cables you would need.
perhaps some of our 70's members could post some pictures of the set up!
you call them ferrets, i call them weasels.