Most of the places I know to stop between Walt Disney World Resort
are close to one or the other end. The most direct route would be down US 17 to I-75 and it does not look like there is much traffic starting at 10. It is only a little over a 3 hour drive, so you might not need to stop.
Up near Orlando but a little off the direct route Lake Wales
which has the Bok Tower gardens (but that costs money to see). There is also the Spook Hill
which doesn't cost anything but it is also off the direct route. She might enjoy the Ringling Circus Museum
but that also costs to enter. And near Naples there is the Corkscrew Swamp Sanctuary
but that also has an entrance fee.
There is also Highlands Hammock State park at Sebring
(only costs $6.00 a car). That is about an hour and a half from WDW and would add about 45 minutes to the trip. They have a little museum and a boardwalk out over the swamp. Then you could eat someplace around there and it would be another 2 hours to Naples. Or you could go to Corkscrew Swamp (they have a longer boardwalk out over the swamp) and eat in the cafeteria there. That would make the total trip over 4 hours.