since you are gutting.
in my opinion?
i would lose the lower ceiling and the fibreglass insulation mark and pull the wiring out run conduit for the wiring in the upper ceiling where the fibreglass insulation was and after the conduit and wire is done then spray foam it and finish the ceiling back to the curved section and gain that head room back.
especially i you want to insulate the floor.
just a quick opinion and alot more thought about means and methods would need to go into it?