So we are planning to stay over at a Cracker Barrel for the first time this March when we head to Florida. How do you find water? Are there places that typically allow you to fill up 10-15 gallon...
Will you have already de-winterized? Otherwise your going to need some time to flush out the anti-freeze material and then refill.
You may be better off stopping somewhere near the NC line and adding 10 gallons for toilet use only, and carrying a couple of gallons of bottled water for toothbrushing and morning coffee.
As far as just adding a small amount for the toilet, Loves on I-95 near the NC line has a water faucet near the tire shop.