I am at the opposite end...purchasing an RV, but searching for cabins is possible through a convoluted two source process. You start with RV Life Trip Wizard (small annual cost) and when a site is located - will address shortly - the campground page will have a "website" link that jumps you right back to this US Military Campgrounds and RV Parks web site.
Now, the quirkiness of TripWizard. It is designed for trips, not simple research. To get past that and access all other features, I created "Test Trip" with no destination, simply going to the map and scroll. For example, start in Florida (my home location) and scroll up the Atlantic coastline to Maine where all campgrounds appear as scrolled. DOD/Military campgrounds stand out with a US Flag icon, Nat Park service has their own, State Parks, commercial, etc all with their unique icon. The map view has a dropdown menu to filter results, one of which is to limit it to "cabins/on-site rentals". You can also filter limiting to DOD/Military, but since it has such a distinctive icon, usually leave it open. When identifying a location, choose "website" to jump over here for details, phone/contact, costs, etc. As a secondary benefit, the TripWizard has user reviews that are independent of the campground reviews posted here.
