The photos aren't squared up on flat ground and taken at a square on angle. I know you were on your own and did the best you could. From what I can see, he has very good conformation. HIs back is a bit on the long side and he seems to be built downhill. I am sure he'd do well in WP.
One note on the "free lunging" you were doing. You don't want to do too much "clucking", especially if he is not reacting to it by making a noticeable change. YOu cluck when you need him to move more (you were clucking when he was doing ok in the canter), when he goes, stop clucking. And, if you cluck at him and get no change, then by gosh, get in there and GET a change. You will make your clucking become meaningless background noise, which I think the horse is already thinking.