REI has some organized local trips where they supply everything and transportation. The DC REI doesn’t do backpacking/camping rentals last time I checked. You’d probably be better off looking into local groups or finding a friend who shares the same interests who maybe has excess gear unless you want to rent or buy.

Nothings stopping you from renting a car and finding a gear rental place. I’d be surprised if you couldn’t find gear rental places near Shenandoah or the more popular WV hiking and camping spots. Might be more rental places in the DMV burbs.