The state line is the first campaign boundary, not the drive time ring
Kentucky clicks and Indiana clicks should live in separate campaigns with separate money, because they are separate businesses in every way that matters.
A radius has no idea that Clarksville is in another state. Set geography by county instead: Jefferson, Oldham and Bullitt on the Kentucky side, Clark and Floyd on the Indiana side, each with its own campaign, its own budget and its own landing page.
Registration, tax and insurance requirements generally differ by state. If you are set up for one side only, exclude the other outright and stop paying for inquiries you have to turn down. Worth confirming your position with your own counsel or insurer before you widen the map.
Say it in the ad copy as well as in the targeting. A line naming Southern Indiana, or naming the Kentucky counties you serve, costs you nothing and filters the click before it costs you a dollar.
Use location of presence rather than interest where the platform allows it. Somebody in another state researching a Louisville pool is usually a relocation, and a relocation deserves its own message rather than being mixed into your local auction.