Are you looking to gut a unit for the purposes of making it livable for a few years? Or are they two independent ideas? What I'm trying to say is you don't need to gut a unit to find something suitable to live in for a few years. In fact I would advise against this. Full time living can put a lot of wear and tear on a trailer. Best to find one in solid shape that you can adapt to your needs and go.
Gut, shell off renovations are more hobbyist projects that a can be very expensive and time consuming. Do this if you wish but don't do it if the goal is to just have a livable trailer. Unless you have extravagant tastes and you want to dump 20K or more into the trailer to have something very custom and unique. As others have said, you can pick up a fully functioning 70's trailer for under $10K. You can get an 80's or 90's for not much more.
Another thing to keep in mind -- if you are going on the road with the trailer full time -- is that you need to build it right if you are going to create a custom trailer interior. Weight counts. Construction counts. Don't think it will be easy to create a lightweight interior like they did with original interiors. Don't think about buying prefab cabinets and plopping them inside (far too heavy). Crafting an interior from scratch in a way that looks decent is fairly skilled work. Renovating an existing interior that is in good shape to start with can be done by lots of people.
Texas Gulf Coast Unit, Texas Airstream Harbor
Angelina National Forest, Zavalla, TX