I started doing this when I made period neighborhoods. My sims would be dressed in era clothing and a random townie would come by dressed in a crop top and mini skirt. What I do is, I have made a Convent in one hood, and a sanitarium in the other. The leaders of these lots, takes in townies into the family, sometimes I change their names, and then they choose from the household closet some new digs. When I'm satisfied or when they are "rehabilitated" they get sent back to normal society.
I use simblender for this. I also take the lead sim to the town and buy up a variety of clothing of all ages and genders and then it makes the process easier.
I actually play majority modern neighborhoods so this is how I get around having the choice of maxis townies when I want them or need them without having to have default replacements or mods to get rid of them altogether.
Peace, Harmony & Balance... Libra is Love..