Hi Vick,
I've flown into Gravely Valley...it's sort of a strange place. Regarding the approach, they say it's a one way strip, but in a Cessna 140 I found plenty of room to land either direction, though I preferred to only depart to the south. The topography should make it pretty obvious that with any sort of wind things could be squirrely.
The northern end of the strip appeared to be a popular shooting area, and a road vivisects the southern third of the strip, so there is some vehicle traffic. A few donuts had been spun in the runway...a few hundred, actually. I know there is a campground on the south-east corner of the runway, but I don't know if it's "open" in the winter...it appears to be there for the OHV folks, not the flyers. Camping anywhere on the strip or in the bush would be no problem.
When I was there in January of '07 a heard of elk was taking up a lot of the southern half of the strip. I don't know about the fishing in Lake Pillsbury, but I don't see why there wouldn't be at least a couple trout somewhere in the lake. Hiking seemed lackluster at best, and honestly I wouldn't leave my plane unattended on that strip for any length of time. I'd also bring a gun or five, as something about the area just screams white trash and meth production to me. That's just a gut feeling based on the area, and on eyeballing the handful of people who drove by while I was there, but my gut feelings have been accurate more times than not.
Cell phones do not work from the strip, but there are a few homes close by, so summoning help shouldn't be too big a problem if you blow a tire or are otherwise disabled. As far as I know there aren't any tie-downs, so bring the makings for your own.
I've only been there once, so there might be a whole lot more to the area than I'm telling, but that's my take on it. Maybe sometime we can fly over there together and take a closer look.