I have made several trips to Panama City Beach from Tampa. The distance from Lake City to my destination is 218 miles. At Lake City, I charge to at least 250 miles rated range (roughly 95%-98% on my P85). I take I-10 until I cut off at State Hwy 12 to start the trip south to PCB. On I-10 I set the cruise to 68 and stay in the slow lane. After I exit I-10, my average speed is around 60-65 because of the smaller roads and small towns I pass through.
Using the above, I typically arrive at my destination with 15-20 rated miles remaining. The lower number occurred when I experienced thunderstorms the last 30 miles of the trip.
I think Lake City to Defuniak is doable, but you will really need to watch your speed on I-10. I think I would be a lot more paranoid trying it in a 70D.
A little guidance for those of you who stop at the Sheraton in Tallahassee. If you decide to walk around the neighborhood after eating, stay on the main drag (Tennessee St) or points south. The area to the north and east of the hotel can get pretty dicey.
Another option in Tallahassee, although slower charging, is the Whole Foods market at 1817 Thomasville Rd. they have two free J1772 chargers in the parking lot. In addition to the food area at Whole Foods, there is also a "Burger Fi" hamburger shop that is pretty good. I have charged there on several occasions and have gotten roughly 18 miles per hour of charge.
The strip center also has a nice shop where you can pick up all of your necessary FSU clothing, tailgate accessories, and other fine goods.
if you are a member of the Fl Tesla Enthusiasts group, there also is a member in Tallahassee that has an outdoor HPWC available.
Good luck on your adventure.