I’m looking to convert my vented attic into a conditioned space for multiple reasons.  The attic houses the A/C air handler and all duct work for that side of the house.  The original fiberglass batts are a mess and not even remotely close to code and there is subfloor in half of the space, not to mention substantial air leaks throughout.  The attic is regularly accessed for storage, so blown in cellulose is not an option. 

I was strongly considering R-30 mineral wool between the 2×8 rafters and then 2″ of rigid foam fastened and taped to the rafters.  After much research, it looks like vented rafter bays would be required.  There are soffit vents on the low side, but being a shed-style roof, there is only a gable vent on the vertical wall of the ridge side.

I am trying to avoid closed cell foam due to cost and the inability to DIY.  The roof was recently replaced and unfortunately, I did not think to insulate on top of the sheathing.  Do I have any other options?  Any help would be greatly appreciated.  

I’m attaching a picture for reference.  Don’t mind the Halloween decorations – it’s an old pic.  We’re not there yet.

The house was built in 1977 and I’m in southern NY.

Thanks!
Adam