What I'm finding here in VA, is that campsites are kinda like a motel..."check in" is in the afternoon. If you can arrive at 7
am, and hang out, I think that might secure you a first-come, first-served spot. You may not be able to
occupy that spot until around 3 pm though.
I think you can backcountry camp anywhere along there, as well. As far as "pet-friendly", I wouldn't worry about that at all. At worst, you may just get charged a small pet fee. If you are looking for any kind of "solitude", however, I'd get far away from Shenandoah and Skyline Drive on Memorial Day.
