Many thanks to DJ for a great set-up and stay. The cabin is a real find in an area that's mostly camping/RVing.
Glendo State Park is very close by, although the weather was quite cool and stormy during my stay. Not a hardship, though, as I thoroughly enjoyed the cozy cabin, and working on music and projects.
Notes: There are trains across the road, but no train horns, so I didn't find them bothersome. If you want to enjoy cooking in the nice cabin kitchen, bring food with you. Otherwise you're pretty much limited to snacks from the general store and Sinclair C-store, or driving the 60 miles to and from Douglas.
I look forward to staying again when I'm in the area!