I am rooting for your success with this. Also, ensure really good bleeding of all of your calipers. E/H disc systems are very sensitive to air in the lines, and the first symptom is increased lag time from stepping on the brakes until trailer brakes actually produce brake effort.
If I had thought of it the last time I had mine worked on, I would have had Earl's Solo bleeders installed.
Also, be careful of the length of the installation bolts that you use. Too long and they will penetrate the base housing. I don’t remember the specified length, but there is at least one video that speaks to the issue on YouTube.