Some projects should be left to the professionals
The idea of bringing a vintage camper or vintage trailer back to life and restoring her to her former glory seems like a great and dun project. Realistically there are many pitfalls in the restoration process, and often the inexperienced amateur should get some professional advice before embarking on a large-scale project.
This type of project should be for ones use and not for resale. The most commonly forgotten aspect of a restoration is resale value. Its going to be far less than the time and effort you have put in. Also keep in mind, you are dealing with a 50-60 year old piece. Be sure the structure is solid before you worry about the decorations.
Be certain you are putting your time and money into a fundamentally good design and structurally sound trailer. The value of the camper will be much higher when you are finished, and it may be easier to sell. We often see a "restored" trailer that is in really poor structural condition. A quality built trailer from a well-known manufacture will be a much better start on a restoration than most others. This is a very good thing to consult a professional about, because to the untrained eye all trailers look pretty much the same.
Remember fresh paint on a rotten old trailer, is just putting make up on a pig. If you do a proper restoration, you vintage trailer camping experience will be greatly more enjoyable. When it comes time to sell, you can get rewarded for your efforts.