Grouping up worlds in an idea that I'm currently thinking about ways to implement. A tourist toggle like you suggest seems like something that should be possible, I'll add it to the list.
I’m excited to see what you’re able to come up with! One more question, though I feel like I saw this asked somewhere else, I just can’t find it: is it possible to view in game what world homeless sims belong to? And then to assign/reassign them? NPCC has a function for assigning sims to different jobs, so idk if this would function similarly.
I scrolled around some more and found the thread where this was brought up.:) so, it may or may not be possible within the mod? But, moving sims changes their resident status? So, in theory, if I have an empty residential lot in, say, Sulani, I can move all the homeless households that I want to be identified as Sulani residents into that lot, one at a time. Then I can evict them from that lot, and they will become Homeless again, but they will still identify as Sulani sims? It could be tedious, but would that work…?