My house has a garrison style overhang of the 2nd floor in 4A.  I am planning to do some work where I would need to take down the plywood soffit and the only insulation is a single piece of old fiberglass batt acting as the barrier.  I realize cut and cobble is not the optimal solution, but I think it’s the easiest and won’t mess with the details of the siding/soffit.  The kicker to this is the overhang has HVAC ducts running down the joists which turn upwards into the 2nd floor bedrooms.  So where I would normally want to put a piece of rigid foam directly on the top plate in-between the joists, I think that would let conditioned air condense on the rim joist/subfloor above?  So my plan is to cut and cobble rigid foam against the rim joist inside face and then cut and cobble a piece on the bottom side of the joist that would sit on the top plate of the 1st floor wall and run to the rim joist.  I think that would then make an air barrier where the conditioned air would stay inside and any moisture could dry inwards towards the house instead of being given a chance to condense with the cold air?  Any thoughts or discourse to my plan?