Purchasing land to live on in DC area - zoning questions

your asking the wrong people ,go to the county court house and ask. and I,d get it in righting with there name when you are approved, get the facts then fight your way thew the paper work. everything on paper, BS don,t get you no where.

I am not sure "relatively rural" near DC exists - depending on your definition of "near". We lived in Frederick County MD and had 6 acres and was able to keep my MH in my driveway. Very rural where we lived - actually about 2 miles from Camp David in the Mountains. But that was a house, with water, sewer and electric. In MD zoning for keeping an RV isn't state or even County specific. It comes down to covenants in a particular neighborhood. But again, that's residential. The further you get away from DC the more available and affordable land is. Where we lived was about 1.5-2.5 hours away from DC depending on traffic (and there is a LOT of traffic via 270). Lots of people commute to DC from Frederick and even as far away as Washington County MD. I can't speak to things heading East toward the bay.

My advice, pick a distance you can tolerate a commute, contact a realtor, and start looking at land. But buying a plot of land just to keep an RV with infrastructure to support it, would be something akin to a modular/Mobile home. installing Septic or tying into public septic is costly and requires a lot of paperwork and inspections. In some counties putting a hole in the ground will cost you $20k in impact fees.

Maybe a Farmer would lease you a piece of land and avoid the headache altogether. Or look for "game land" or "recreational use" property and get someone to hook up electric and sewer on the down low.

In order to get a well or septic permit in a rural county area will require a plan for building a home or garage/business in the near future.
Your best bet would be to look for a location with a recent fire or other event which would allow a location with existing well/septic/electric to be used the way you wish without overt government scrutiny. Even a location with a "still standing" trailer or mobile home, again, anything with functional well and septic in a location where you can be discrete......

Otherwise, I would look toward Richmond or Essex county Va.

Land like that is going to be tough to fide anywhere close to DC. Just because no one can see it without trespassing doesn't make any difference. The zoning laws are going to get you. You will need plans to get the permits for septic, water, and electric, and inspections after the install.
The further from DC the easier, but you will have a long commute.
Maybe W. Virginia.