You’ll need to book the rental car far in advance – those sell out in July. If your schedule is flexible you may be able to wing it a bit and book last minute but you’ll need a flexible budget and a flexible attitude about where you stay as well. Some small towns have limited accommodation so if its full, you might have a bit of a drive to the next place. Or you might have to be content with paying a ton for a high end place. Or you might end up in very basic accommodation with shared bathrooms (like at some older B&Bs). I wouldn’t recommending winging it when it comes to accommodation, but I think with some flexibility, it’s possible. If you can book things a day or three in advance rather than the day of. Have a great trip!