@ Mike again on the post 40, after reading a little more, I agree as I said above yes the GFCI can be RPBG wired ahead of it and still function as if it was wired correctly, and as you pointed out any current flowing in any other path that do not take it back through the current coil in the GFCI will cause it to trip if it exceeds the .005 amps, but in that post you made the commit that you thought there was a way that would defeat the GFCI from detecting a ground fault, and I don't think that is passable as any current that flows from the hot through the current coil must flow back through through same current coil or the coil will develop a voltage and trip the electronics, and the fact that all GFCI devices newer then 1996 will have the 120hz injection coil that will keep anyone from boot legging the ground from the neutral any where down stream from a GFCI device whether its a breaker or receptacle device, this does not not hold true to AFCI's as they do not have the 120hz injecting coil and that is why if you have a grounded neutral on a AFCI circuit it will not trip until a load is present.
I will say you are on top of the rest of it, and have offered some very great advice. again look over that PDF I attached to the previous post as it is a good reference for those who would like to know how a GFCI works, the writer is a very well known electronics publisher who has written many thousands of books on electronics and is most well know for his "Sam Facts" booklets that many of us used to repair anything from radios and TV's and even had a series on CB radios, and are highly sought after as they included all schematics for many of these electronic appliances.
Wayne A. From: N.W.Indiana
Be Fair, Be Safe
Just don't be fairly safe