We are leaving tomorrow from central PA , and use exactly the same route , 81-77-26-95 (usually if weather permits) . We also avoid RT 4 in the orlando area and jump on 417 around Sanford and its a straight shot into WDW . Well worth avoiding RT 4 Orlando traffic for the cost of a couple tolls on 417 .
We usually do the drive with one overnight stay in the RV . Cracker Barrels are great and plentifull on the way down . Most have parking spots for RV's and allow overnighters (we always eat there to show our thanks) . Not all cracker barrels have RV spots , so its best to check ahead , I use google maps to check ahead of time.
We don't do Walmarts ..........just a personal preference . They always seem a little sketch and a lot of them are not allowing overnighters anymore, so its hit or miss .
Rest areas are a good easy option , but the Trucks can be loud . Air brakes, running engines , reefers , coming and going all night , etc. We do these if needed . Usually nice big truck spaces , and some even have RV spots .
If we are making good time , our normal overnight stop is the Cracker Barrel in SC on route 26 . Just past Columbia in Orangeburg SC . Great stopover, about 5 RV spots , quiet location and usually several other RVers so it feels more safe. Last trip down there were about 10 RVs parked overnight . There are lots of Cracker Barrels that fit the bill .
If we are getting tired , or had some slow downs on the trip , another great stop is the Cabelas on 77 . Just past Charlotte on the way down , right next to Carowinds amusment park . Its literally on the NC/SC border , just barely into SC . Lots of places to eat close by , lots of RV spots , and they even have a dump station . Nice quiet stopover, and feels pretty safe and usually there are other RV's overnighting too .
Just use google maps satelite view and try to narrow in on a location you might think you will want to be stopping . Look at some places in the area ( I try to narrow in on Cracker Barrels) and see what looks good for overnight stops . Cracker Barrels are prob about 90% RV friendly with large pull through parking spots . If the RV spots are full , its usually acceptable to just pull in a few of the car spots in the back somewhere and park for the night .......just try to leave kind of early so you dont block up the car spots for patrons when they open in the AM .
Good Luck , and safe travels .