I am wondering what is the best way to insulate a cantilever space containing hot/cold supply pipes and a bathroom exhaust vent. Above the cantilever is a bathroom, below is the entrance to my house and on the inside another bathroom. Currently there is only fiberglass, no blocking, no foam, no sealants. The pipes have been there since 1984 and since I live in a middle unit townhouse they will not be moved.

Should I install rigid foam just below the living area sub floor as well as just above the exterior sheathing/ceiling? Also, should I build a rigid foam box around the pipes to slow outside air from getting in but then leave the box open to the conditioned air from the house?

Here are three pictures.