I read many forum topics about the question...
As the road will be a single track for many kilometers, a single wheel trailer seemed to be the best solution.
I discovered two main trailer constructors:
- Bob (http://www.bobgear.com/
- Aevon (http://www.aevon-trailers.com/
These constructors use different fixing solutions. Bob trailers use rear axle fixation whereas Aevon ones use seat tube solution.
I decided to make a trailer as similar as possible to the Aevon trailer.