Not necessarily true for overlapping lots, this kinda lot can still be shared and made multiple copies at once by file replacement at lot folder.

As long as the dummy replaced lot fits in the original lot specs of the expanded lot, just copy the lot for multiple duplications and rename them accordingly. I don't see that a hard job to do so.

Yet, for further convenience, shrunk stable lots should be the best choice.

A lot file seems to record the fence posts to record where the walls and fences are at. What do you think?
How to fool the game to recognise the walls as fences while avoiding the gridline atop of the walls to cause crashes?

As previously suggested, I surely back that Inge's portal revealer to post out the wonderful mod.