Pringles, the hay of 1903 was almost certainly loose and piled to the rafters in the gable bays. It was common in that era that barns were furnished with hay tracks with trolleys and hay forks that would pick up hay from a wagon in a central and move the hay overhead to a gable bay, four legged horse power, or it could hand loaded. The knee walls sound like skirting around thw threshing floor to keep the grain and hay from mingling. Threshing in 1900 could be done by hand or by machine, power could come from either a horse on a tread mill or a belt driven pto on a steam tractor. Ag museums and steam tractor associations could provide live re-enactments. Google the topics for more.
In my home area, bank barns do not commonly have hay lofts, hay was piled on the floor and moved to the livestock throwing the hay down a hatch or out a door on the forebay side ie the side opposite of the ramp. Some barns have a sheet steel lined granery. Floor joist are hewed on two sides to about eight inches deep from oak poles about 16 at the butt and 10 at the tip. The joist run ramp side to forebay. Forebays tend to sag under load.
