Is there any chance the valve covers are leaking? If those other seals were leaking then the valve cover gaskets most definitely are, have been, or were already replaced. They leak all the time with age. They leak at the very back lower corner just above the crossmember and blow back from there as you're driving. Which then migrates down towards the same area you'd see the leaks you're describing.
If it's coming from between the engine and trans then it's likely to be the rear separator plate rather than the main seal. Make sure it has a metal separator plate and seal it.
If it's consuming oil - that's not a big deal, just keep it topped off and hope the PCV valve helps. Also the hoses around the PCV are likely to be brittle and fail while you're removing it. Might want to have those on hand. Generic hose is hard to make those bends in tight places and tends to collapse but can be used in a pinch.