I am having some fun researching an adjustable draft carriage hame design from the mid- to late 1800s, and preparing to run some experiments. I enjoy blogging and have condensed all I have found here: understandingharness.blogspot.com/2018/02/bencraft-hames.html
By the time the weather improves, I should have an opportunity to test it for myself. My little Morgan mare has always been a challenge, having deeply sloped shoulders that are very hard to match to an optimal line of draft. So I'm looking forward to the results!