It seemed that as soon as I let go of my plan to start showing him this summer, the tension just melted out of both of us. I also decided not to sell him ... at least not this summer. That also helped us relax. If all we can do for the next however long is walk and trot, then that's what we'll do. I'd rather have a lot of safe and happy walk/trot than a little bit of Oh, crap! cantering.
So what have I been doing? Lots of walking and trotting while asking, asking, asking for a long and low neck. To the right, the side that bends reasonably well, he can stretch way down, and he does so with very little resistance. To the left, his stiff side, it's a whole other story. When we go left, I have to walk a fine line with the outside rein. If I let him have too much, the circle gets huge and he won't make the left turn. If I take hold of the outside rein with too much strength, I can feel him get tense. He doesn't like the feeling of too much contact. So I use a ton of outside leg and a medium amount of rein to ask him to turn. I also rock the inside rein to get his neck to let loose just a bit. I squeeze him forward and give him every opportunity to reach and stretch through the bend. When he does, I soften everything and praise him like he's just won Olympic gold.
It might be a slow pokey way of accomplishing long and low, but it's working. There's no bolting or rearing, and his ears stay soft and floppy. We might have to do this all summer. We might have to do this forever. I am pretty much okay with that as long as I feel safe and he seems happy. For now, it's a pleasant way to spend a half an hour.