Insulating next to a narrow basement stairway in climate zone 5A – GreenBuildingAdvisor

My home has a narrow set of basement stairs (28.5″ clear space from outside of treads to stringer) and only 1.25″ from the stringer to the exterior CMU foundation wall.  I am finishing my basement and trying to figure out how to insulate this wall without eating up too much of the width of my staircase.  So far the best option I have been able to come up with is below, but I am curious if there are any better alternatives that I should consider:

Parge coat on CMU foundation and paint with epoxy paint

Install interior drainage mat on inside of foundation wall with seams, tops, and penetrations sealed.  Channel into interior perimeter drain

Install 7/8″ 16-gauge metal hat channel affixed to stair stringer at bottom and an extension of the sill plate at the top (1″ total gap from drainage mat to rear of hat channel)

Closed cell spray foam insulation to fill space between wall and hat channels and cavities between hat channels