The easiest answer is to say 'both'.
The brain-tanning process used was and old, tried and proven method and would be seen for many years to come, but those who 'made' the clothing - the women - 'really' liked the pieces of tent canvas and salvaged tent cloth they could get from the Army, because they could bead their designs onto the much lighter fabric, and once finished - 'then' they could attach it to the garment as an applique'.
It was both a time and effort-saving and finger-saving shortcut, much as the overnight acceptance of the steel sewing needles were., since it's a tedious business, beading onto buckskin.
In that leggings did take a beating, but were also durable, but cloth ones were by that period - were in a general use throughout the tribes, and it was high summer - I'd venture there was an equal mix of both, as well as bare legs.
Vaya,
Scouts Out!