Others may disagree, but my approach with Charlie was to start small and easy! Your guy is young so you have to account for the fact that he’s probably not sure what you’re asking for, on top of being in some discomfort.
The goal with pole work is to build up strength, coordination and proprioception. It’s NOT going to be there in the early stages. Heck, when I have my stuff set up for Charlie and the other boarders use it, they are banging and knocking stuff down WAY worse than we are
I started with a single pole. Then added a second, a third etc. I also started with as perfect spacing as I could get so it was easier on him since I know there is a pain element. Then I started with raising the poles/making them uneven etc. Make it fun!
Check those Jec books out! They are VERY prescriptive so youre not just drilling the horse as well with the same thing. It’s a lot of back and forth and different exercises. Here’s one of our workouts as an example; we have a bridge to do the step up/downs and up and overs.
It took Charlie some time to really figure out the pole straddle too but that’s helped with proprioception
I’ve always done groundwork and liberty, but we really amped it up last year going through everything to keep things fresh. We learned how to push the ball last week and he’s had an absolute blast with it. All of this type of work has been amazing for bonding and communicating with each other. I figure at some point, riding isnt going to be an option for us, and the groundwork is ALMOST as rewarding as the riding. So I’ve been challenging myself to make the most out of it and have found a lot of laughter in it.