SMALL HORSES IN SHOW RING
Keep in mind large pony hunters (13.3-14.1) jump 3' courses and the distances are set for a 11-12 ft stride so there is no reason why your 15.2 hand horse couldn't do the 3' AA's.
One of the horses I ride is only 15.1 and when the fences are bigger the easier it is to make the strides. Since he is a smaller horse he is more impressed by the size of the jumps and actually jumps much tidier and more expressive then some of the 17 handers who just "step" over the fence. Also, he wins the hack a lot....
Years ago I rode a 15.2 hand paint who had a super jump and a huge stride, he won everywhere.
A good judge is looking for eight perfect jumps, seamless lead changes and a happy expression, regardless of the size of the horse.