Welcome! CO resident here but I grew up where you are now. No shortage of outdoors things to do in the Black Hills for sure. During August it can be hard to accomplish anything near the rally except experience the rally. It's a good time for a vacation. Grab those resident elk tags before the state figures out how much money they could be making off non-residents! Ft. Meade is a good gig, she'll probably run into my dad...hopefully not literally, I keep telling him to get a ride from the DAV and quit driving himself to his appointments. You probably guess how effective I am at telling a retired USAF E-9 in his 80's what to do.
OnX is great. I used the gps chip for a bit, but now I am trying to find a way to carry a lightweight power bank because the phone app is that much better.