I'm not sure you can overnight at the Tamarack facility but keep in mind it is part of a huge rest stop/service area. I'm sure you could park somewhere. Call them and ask where you can stay for a while or just pull in with the 18 wheelers.It's too close to home for us to be spending the night so I can't be sure what advice to give you.
We always stop there on any trip down I77 because they have a huge parking lot for RV's on the lower level below the facility on the hill. On many trips we stop there to make a sandwich and stretch our legs. They have very nice gifts made by West Virginia craftsmen and a restaurant that is class A. It is actually part of or managed by the Green Brier Resort I believe. The food is great. We always spend an hour or so there just walking through the gift area. Don't miss it.
The roads coming off the Interstate are a little confusing going into the parking areas so watch your signs. Otherwise it's a great stop.
Good to know they allow overnighters. Even though it's only two hours from home I may at some point need to stop for the night.
The Tamarack facility sits on the hill overlooking the service area for food and fuel. There are two access roads leading into the parking area for RV's . We always enter the first one from the loop road and then pull down through the auto parking lots into the one for
Rv's. As we leave we pull straight out of the lot and turn left heading back down toward the service area.