I'm just starting work on a couple of medieval wagons and thought I'd look up some bits about harness. I found this article Gail Brownrigg : Medieval Horse Harness – The Evidence of the Images
(https://www.academia.edu/116600511/Medieval_Horse_Harness_The_Evidence_of_the_Images) from 2020.
I deliberately didn't title the post Medieval Wagon Harness because, in fact, it says as much about pre-medieval harnessing arrangements so is of more general interest. It leads with another piece of myth-busting (and, as we know, I like a bit of myth busting :) ) about the medieval harness "revolution".
Nice find.
People interested in earlier harnessing may find Roman Traction Systems - http://www.humanist.de/rome/rts/index.html - useful.