I think both schematics in post #15 have issues. In the upper schematic, the right-side pass transistor might be in backwards. If you want to turn it on by pulling its gate down to GND, it should be in there as common source rather than source follower. This presents a backflow problem through the body diode, which is why the standard circuit for this has two FETs back-to-back. I might be wrong, because the part is drawn PMOS but marked NMOS, so the exact circuit function is not clear.
As a cross-check on the basic signal flows, substitute a PNP transistor in the drawing and see if things behave the way you want.
ak