I ended up doing a custom save template without really meaning to do it. I just kept changing things to what I needed in my game, like fewer repeat venues to keep down the number of NPCs spawned. And my worlds tend to become theme worlds once I develop them, sort of like each world eventually becoming a unique vacation destination for my main sim family.
I did not really notice how long it took, because the fun was getting there. I am almost done with a full makeover of each world that I intend to actually play in. And the small handful I will ignore are mostly wiped of all lots except for the one that is required game play, like my solitary vampire and solitary werewolf living in their own house being the only thing not wiped in those worlds.
One thing I will say now that I am on the tail end of doing a custom save template, is that I am so glad I did it. Playing a custom save is much more fun than living in someone else's idea of what this game should be.