The SMB Elites, are very low profile, and with the height no higher than 2'3, he shouldn't have a problem with movement.
You could just polo wrap him as well.
No boot will take all the impact away. It'll help, but his legs will still take quite a blow from landing. Like I said though, the Elites are very fitted. I've seen them used in the dressage and jumping rings for schooling with no complaints.
I use the Legacy boots on the fronts, and even as bulky as they are, I've never felt they affected his movement.
I have had my seniors on SmartFlex senior for awhile now, and they certainly have improved off of it. Side thought....
"You're just as sane as I am."~Luna Lovegood.