What you described is exactly what I did. I'm actually about to update this with different screenshots because I reorganized it to put my Royal Garden next to my Palace set. I moved the Shrines and the Manor to a different area as well, where they're part of the city at large and aren't grouped with the garden and palace.I'm a little late to this party, but as a plunderer, I'm going to critique this strategy a bit.
Disconnecting roads is a pretty poor strategy for deterring a plunderer. It might deprive the plunderer, but it WILL deprive you. Disconnecting the whole city is just ridiculous. However, a more limited disconnect isn't too bad with the new building sets. I arranged my city with that in mind just in case:
I'm also updating it to remove any humor I injected into it, because apparently no one can take a joke. That's not directed toward you, it's just that thus far, I've received a significant amount of trolling, being made fun of, etc., with precious little actual help or suggestions to make things better. Add that to taking the whole thing far too seriously, and it's making me regret ever posting in the first place.
At any rate, I think updated information and screenshots will help, because people are reading this as 1) disconnecting my entire city, which isn't what I've explained nor is it shown in my screenshots, or 2) that I'm leaving the entire section disconnected indefinitely, which is not the case. Do check back in tho, because I've made changes and am happy to finally receive actual feedback.