Zone 4 (SW MO)

I have a large storage space over a garage that is currently unconditioned but may do so at some point. Right now the 2×6 rafters have r-13 with no venting at all but everything is solid and clean. Was built in the 90s. 
Floor has unfaced r30 fiberglass installed recently as I replaced the wafer board flooring so threw that in while it was open.

Thinking of insulating it better since if I ever did condition it, it would need it.
I would need to crunch some numbers but my thought is 2″ of xps (reclaimed) fit between the rafters and foamed around the beveled edges.
Then 3.5″+/- of closed cell foam sprayed over the xps.

Not worried about the time involved with the 2″ as it wouldn’t have to be done all in one setting

I just want to ensure there aren’t any issues with doing this
1) in general
2) with it not being conditioned [maybe never] (yes, waste of money)
3) if it is conditioned in the future
4) if I install the 2″ edged-foamed but don’t get it sprayed foamed for awhile

I realize the r-value still won’t be great as far as the numbers go.

Also, open to other non-vented suggestions. I could put ridged foam on the underside but would need some help on the best way to fill the bays as full closed cell is a bit cost prohibitive. 
Thanks