I always go back to basics when confronted with a complex decision.
Sarah, you had issues with spending the money for an autoreverser. Then you had many questions about if you needed 1 or 2 insulators on the "reversing loop" section. Then there were lots of questions on using a DPDT switch to manually reverse these sections. Then you reported one reversing section worked, but not the almost identical other one. Later, apparently, neither reversing loop worked.
So, back to basics... are you going to continue with track power? If so, then decide if you are staying with DCC or not. Then if you are staying with DCC, get a decent power booster and then you can determine if you can handle insulated sections, and reversing loop electrics.
If no to any of the above, then make the decision to give up track power entirely, please.
Why this long diatribe? Because you have shown a layout with a "reversing loop".
I won't enter the track power vs. DCC vs. remote control controversy, but none of them is completely trouble free... you trade one set of potential problems for another. Which set of problems is larger is the debate.
But, at this juncture, given all the history, I would say go R/C, and then your track plan can be anything you want, and you don't have to worry about conductivity, reverse loops, power feeds, a booster for your underpowered (for G scale) DCC system, etc. etc.
With all that said, I think the plan you show has too many mainline switches to start, given the difficulty you have communicated with switches... so I would build this in stages:
1. leave out the two "switchyards", put in only the folded dogbone.
2. Add the 2 switches for the "reversing loop"
3. Add your switchyards
Since you indicate sectional track, this will be easy to do, and allow you to "debug" problems bit by bit, as opposed to too many things wrong at one time.
Regards, Greg