In my experience, determining how tight, or loose, to hook the traces when hitching a team can be a bit challenging for beginners. This is because a number of interdependent dynamics and variables between the pulling system and the holdback system must be considered, and because it’s ultimately a judgment call rather than a simple measurement or clear cut rule.
My forecart pole is set up for draft horses. My husband thinks we should cut the pole off to permanently make it fit better to these smaller horses. What would be your opinion? Like your husband, my preference would be a shorter tongue for a small team like your Fjords. The dynamics and efficiency of draft are better if we have our horse(s) close to the load. A shorter tongue will also reduce the overall length of your outfit, thereby giving you better maneuverability and turning dynamics.
What I have come to call the “triple tree trainer” is simply using a three abreast hitch to bring mules along slow and deliberate to train them to pull triple, double and single. I am certain that I am not the first to use this device as a training method. I first saw a tongue designed similar to this hooked to a restored fire engine at the Mule Day’s parade in California. It was then, as I studied the hitch, it occurred to me that it would be very useful in helping me overcome some difficulties in training mules to the tongue and to shafts.