Hi OP, I have a horse that is in a very similar place as yours, just learning to canter courses and lines. The difference is, my horse is HUGE and has a massive stride. I know he will walk the 3’6 lines eventually. But right now, doing the 2’ and 2’3, we typically do the ads to. I want him to jump in quietly, go straight, and jump out quietly, so we use whatever canter we can to get that done, which is usually the ad. I just don’t want to teach him to get strung out, ever, when it comes to jumping. I also still mostly do not have a lead change, so I want to land in a quiet canter where the simple is…simple. What I do practice is using just canter poles and trying to work on our canter that way. It’s honestly a bit harder, so when we do it with jumps, it should feel easy for him.
I have also been working on getting my horse stronger-hill work, cavaletti, and the such, which improves his canter. My horse basically would not canter on his left lead for months unless we used a small jump or cavaletti that he could land the lead from. Getting him stronger has been key. Then, one day, he literally just started picking up his left lead. That day he ONLY picked up his left lead, and since then, he gets it most days. Talk about learning patience and having to ignore the armchair quarterbacks who swore if “you just get him to move his hips in”… he wasn’t having it until he was ready. When the jumps are bigger and he is a bit stronger, your horse looks more than capable of making the step for the 3’.
I also agree with your philosophy about showing, i do the same. Get them out now while you don’t care about ribbons, let them get used to the atmosphere, and understand the job. My horse struggled with going in the ring and doing a course while his buddies were at at the gate at a show. We couldn’t quite duplicate that at home, but a few shows (and a set of spurs!) really helped that issue and now its really not an issue anymore.
Your horse is adorable and will make a lovely 3’ hunter.