In my experience in breeding that should be fine we won t put a stallion to a mare if he is more then 2hhs bigger then the mare . Good luck i love having the foals mines due next june cant wait.
i dont go a hand bigger than the mare.
also depends on how chunky the mare and stallion are compared to each other.
a chunky mare with large hips to a light stallion who is taller potentially poses less of a problem then a very light mare to a taller very chunky stallion.