Place obstacles on the track to keep the horses alert.
horse shelter - simple storage room on the side and gate to contain horse if required.
Shelter on a budget
Should we even call these stalls? How about small indoor paddocks! How nice!
If you have to have stalls for your horses I love these mesh fronts. Allows for good airflow (less ammonia etc.) and horses are a part of the goings on in the barn.
Morton Buildings horse barn in Ohio.