The problem with scaling the CS 23 down and reducing the sheer line height to make an offshore boat into a bay boat is that you still have the offshore boat bottom with 17 degrees of dead rise at the transom and more draft than you might want or need.
The FS19 already has a bay boat vibe to it. It might be possible that you could add some Carolina flare and tumble home to it by modifying the transom, mid and bow frames. Adding slits to the side panels to accommodate the tumblehome and flare would be required too,
The FS19 that I built is in my opinion a fine looking boat, and based on the number of people that stop my brother every time he uses it to ask about the boat confirms my opinion.
Because of the lack of an interior liner the FS19 has as much interior room as my fishing buddy’s 22 Bay boat, is lighter, more fuel efficient and achieves the same speeds with a lot less HP.
Lots of good designs for bay boats to choose from here.
I love the lines and look of Carolina style boats myself, but your intended use and the design requirements to meet those needs should take priority over the lines of the boat.
Of course there are many versions of production built boats that have been adapted to include Carolina flare styling applied to everything from flats skiffs, bay boats, center console and express offshore boats. A used version of one of these will be your quickest, easiest and probably cheapest route to achieving what you want.
I however would love to see someone adapt one of the BBC designs to achieve a Carolina style bay boat and do not want to dissuade you from your boat building project.
If you don’t do it, perhaps I will.