Just past Wilmington De on 95, jump off on 896 which turns into 301 Stay on 301 to Bowling Green Va and take 206 (I think) back over to 95. Skips Baltimore and DC. Some traffic signals to slow down but not bad at all.
In Florida take A1A west to join 301 again. Run 301 to just north of Ocala and take 326 over to 75 south. I will caution you that several of the small towns on 301 are very strict with their speed enforcement.
Depending on your taste, you might like Koreshan State Park or Gulf Waters RV Park. That time of the year you would have no difficulty getting into either. We lived in Ft Myers before moving out West, and liked it. During the Winter it's tough because they haven't built any roads since I-75 was complete. But in June you'll get around fine. Mirromar Lakes, Naples, Bonita Springs, Ft Myers Beach, Sanibel/Captiva will all keep you quite busy.