Max elevation: 3192 ft / 973 m Min elevation: 2 ft / 1 m Elevation change: 3190 ft / 972 m
Max grade: 4% Min grade: -4.6% Steepness score: 12 + 456 + 1581 + 35 = 2084
Distance: 1075.77 mi / 1731.28 km Travel Time: 16 hours 18 mins
It looks like one possible route that might be flatter would be to go through Texas, but make sure you double check everything if you're planning a road trip.
Elevation data comes from different sources and may not reflect true
driving conditions, so talk to other RVers if you're concerned about
If you really want to avoid mountains, the best route would probably be to go down I-71 to I-65 through Nashville. That gets you around the Smoky Mountains, then you can cut back East to Florida. It does add some extra time, but it's not a huge amount and you avoid I-77 which can be very hilly.
Another option is to take I-75 through Knoxville. That's not as flat as I-65 but it's a little less out of the way. It depends also on where you are starting in Ohio and your final destination in Florida. Remember that Atlanta can have really bad traffic, so you would need to time your driving to avoid getting stuck there.
Also make sure you check the weather conditions for any route you choose!
These are some of the possible highways along this route. Use the GPS in your car to verify all driving directions. If you're looking for campgrounds along the way, search for RV parks between Ohio and Florida.