Is there a secret to finding inexpensive rental cars?

Rental car offices located away from the airport typically have better prices. Can you take a shuttle from the airport to city center and rent from an office located in city center??

How long a drive is it? Is ride sharing an option?

I find that, generally, the cost varies by city. For example, I was recently in San Jose for 2 days and LA for 4. My rental in SJ cost 3 times what my rental in LA did. I spent a lot of time trying to find cheaper car rentals in SJ, but it wasn't possible. I wonder if the fact there is simply way more competition in LA amongst car rental agencies, so the prices are lower. I will also note that I found playing around with pick up times could seriously affect the cost. In a wave of illogic, it actually cost LESS in SJ to return the car later than I intended -- when booking online. The weird thing is that the cost I was quoted online was X. When I picked the car up, it was X-25% and when I returned it, they took another 10% off of that for "early return". Go figure. It's a crapshoot!

I have also found that my supposed AAA discount at Hertz is worth bupkus. I have yet to find any city in which Hertiz is not the most expensive by a LOT, so a discount on a LOT isn't helpful.

Use smaller companies when possible. I've started using Firefly. I LOVE them and they're super cheap!

You may try looking into a car service like Uber, Lyft or Sidecar. Not sure they would be in the smaller cities in KY but it's worth a shot. If you're using a debit card, around here, Enterprise wanted a utility bill plus some other stuff like a pay-stub. Also, no AAA discount with them and they wanted a bigger deposit than Hertz. Went with them instead. They offer a AAA discount and none of this paperwork stuff.

Have you tried hotwire.com? I find good deals with them frequently and the price goes down the closer you get to the trip. They used to let you make a reservation without paying but now you have to pay up front. That part sucks because I used to keep creating a new reservation each time the price dropped and then cancel the old reservation. That isn't as easy now since you have to pay. Also, once I sign up and search, I start getting their emails letting me know when there is a price drop.