I found an old post from 2016 about this rough idea but never had a final answer. 

2 stringers of 2x12s sistered with 1/2″ hardwood plywood between with lauan finished plywood shell and 4x12x40″ douglas fir treads. Rise 52 1/2″, Run 7′ 5 7/8″. open risers. The minimum code requirement of 3 1/2″ throat depth in the 2×12 is met, at 3 3/4.

The local stair building code follows 2015 IRC 311 with an exception of tread depth being minimum 10″ deep. 

I attached my drawing of the idea, does anyone see why this is not ready for inspector review?