"Boler" trailer was originally invented and made by a guy who was in fiberglass tanks manufacturing business.
Original Boler he invented was smaller at about 13ft total length and lighter - under 1000lbs.
17ft variation is twice heavier, about foot wider and quite taller. It was a later design development after the inventor was no longer involved with the company.
I found the Boler trailer history record here:
http://www.proud-canadian.com/13-boler-basics-beyond-1/boler-history/The wall insulation on the trailer was specially made by some aircraft materials supply company as approximately 1/4" thin latex-like foam with white like popcorn interior finish. No longer made anywhere. I still have that insulation in a relatively decent looking shape and it is ok for not too cold nights, but homebuilt Foamies (

) would be much warmer. Some people retrofit the trailers inside with a spray-on polyurethane rigid foam though, which makes it warmer. There are many restorations made. I may keep the trailer even after I finish my experimental build. It is just so cute and it is a piece of history. They are still being re-sold, I see them on kijiji quite often, they last very long time if not abused, like the fiberglass septic tanks do, you know

..
Jokes apart, I agree with GPW that present day trailer manufacturing people need to learn a thing or two from our history proven good design experiences

. Forgetting our world history seems to be fashionable these days.