You'll have to do a lot more work these days to get the hell away from other people in Montana, but IT IS still possible. We just have to adjust our destinations and find legal lands or State Parks that aren't at the top of everyone's list.
You've at least driven right by it 100 times, as this RV campground is smack in the middle of Ennis, Montana. It's been for sale for just a few weeks according to Realtor.com but it's now listed as "Pending".
With trails, campsites and state and national parks so crowded now that the COVID pandemic is on the wane, UM researchers are using the website recreation dot gov to see how and why people choose certain campsites.