Hi, Grant.
Several years ago I bought 2 books on trailer design and building from
Northern Hydrolics, or what ever their name is. They send catalogs
about every 3 months and usually they go into the recycle bin. Can't
find them now to see if the books are still offered. I just glanced
through the books and they look like what you want. I never did build
the trailer. Too easy to go rent what I need.

Paul
Redmond, OR