I am still looking myself. There are RV lots you can purchase in NC but are not close too the beach. Read the fine print. They are deeded lots BUT you can not live on them a full 12 months out of the year.
I would love to buy a lot, put on a pole building for the RV and have a small addition attached with small living quarters. Everything I come across around Delmarva has minimal SQ foot requirements like 1500 sf. I am comfortable in less than 300. No HOA, no association fees, no sewer, etc. I know......keep dreaming.