Agree, you say rootstock is M111, meaning: “. M-111 Apple Rootstock is one of the most vigorous and well-adapted of apple rootstocks , M-111 is a semi-standard tree reaching 80% of standard tree’s height, or 15-25 ft. tall but can easily be kept at a manageable height with summer pruning. Tolerates, wet, dry, or poor soils and induces bearing at a young age.”
Unless you like picking apples at those heights, or trying to get up there to spray them, consider the ability to keep them below heights of about 10’ a blessing. Start tip pruning early, an open center gets sunlight into the canopy and help avoid sheltering pests! So just make sure you spread them as far as you can and keep the branches headed more outward than upward!
Dennis
Kent, wa