Yes, it is possible to have new Plasticoat applied to an Airstream. The product used is different from an automotive clear coat product. Plasticoat is a proprietary product that was originally designed specifically for Airstream. Application of Plasticoat is a demanding process, and there are only a few Airstream dealers or service centers who are offering the service. One of the oldest service centers offering Plasticoat recoating is P & S Trailer Service
in Helena, OH. When I had my '64 Overlander polished and Plasticoated at P & S, they offered original sheen as well as high sheen polish jobs. I chose to go with the original sheen and new Plasticoat and have been thrilled with the results for ten years.
From reading the Forums, there are a number of new products . . . some that began their life in either the boating or trucking industry . . . that have been used on Airstreams to maintain the sheen of Airstreams. These new processes and procedures have been discussed in several of the polishing threads.
Good luck with your investigation!
P.S.: Automotive clear coats aren't typically designed to withstand the expansion and contractions cycles that are present in a polished Airstream . . . at least according to all of the reading that I have done on the subject prior to having my coach Plasticoated.