You give me way too much credit TJ that is for sure...my dumb sheep outsmart me nearly every day if that is any indication of my skills and intelligence.
I am wondering though if you would have to make such a severe back cut if you secured the living trees to each other instead of cutting them so much that they are at right angles. By that I mean grabbing the tops and bringing the top down to secure it to an adjacent tree with rope. In that way you end up with a ton of "hoops", that granted would be higher then your current fence, but without so much of a back cut, or one at all. That might not leave you with
enough density to stop animals, but what if you used the cleared saplings as "rails" between the looped living saplings as blockers?
Now this I have done, and with moderate success. I used fence posts 8 feet on center with saplings nailed between the posts to stop sheep from getting it. Mine worked as long as the sheep had plenty of grass to graze on, but when it got low they started to get out. In that way it failed because I only used 3 rails and sheep like to go under a fence and not over it. I probably
should have used 4 or 5 rails instead, an extra one closer to the ground. And I would not use nails. I would secure the rails to the hooped living trees with wire. Just draw out twice the length of wire you need to go around the living tree and rail, double up the wire,
thread it through itself, then using pliers twist the wire tight. Kind of like how rebar workers tie rebar together. It will hold the rail in place securely, is a cheap connection, and will not kill the living hooped trees because it does not circle the entire tree.
Now this may only be specific to your place as I am going by the photos. In the dead of winter it is hard to tell the species you are using but it looks like popil. I am not sure how easily they can be "trained". I know
Ash and Beech if they are bent over for any length of time, are permanently shaped that way, but I think popil tends to like growing straight. But in this case, you must use what you got, so it is worth trying. And of
course it might be a different species of
wood that you predominantly have.