I'm not sure if it is possible, because I tried for years with an appendix QH that not only consumed groceries at an alarming rate, but scattered the results everywhere and stomped them too.
An overnight stay in the stall resulted in complete deep cleanings nearly every time...
If one has a horse that eats a normal horse amount, and thus makes a normal amount of horsey poo, one can sometimes teach them to be a little more clean, but it is not failsafe...
I have done this with stalled horses, don't know that it translates to outside.
1) start with clean stall, including (if matted) cleaning off the mats with bleach along the front of the stall. Put the water and feed buckets along the front wall, and the hay net in the front corner.
2)After horse poops, place it in the back corner, straight behind the hay net.
3) this is hard to explain, but when cleaning stalls, do not mix up the shavings. Make sure to clean up every bit of manure/urine in the front areas, but continue to leave the poo in the back corner, or at least some of it.
If the horse notices, sometimes they can learn to go only in the back, but some just don't notice or don't care.
IME, stall raised babies are messy, and pasture raised babies are neater.