I don't have anything solid to offer on Cumberland, but I came down US-15 today and the water tower site in Weber City is now up and running with B2/12/4/71 (035ACCxx), I believe I saw new T-Mobile antennas on the tower at Sprouses Corner which I will try to confirm on Saturday (definitely not running if they're there), and I believe I may have connected to something that got converted in Farmville. By process of elimination, my guess is Lancer Park, but I hope to find out tomorrow or Saturday.
So upgrades are clearly coming. You may want to see if your local government officials can tell you anything. Probably not, but can't hurt to ask.
Interesting twist. Today, I took off for southern Virginia and had my T-Mobile B71 phone (Revvlry on Android 10) and I noticed the GPS was bad as compared to my other two devices on SCP on the dash. Couldn't get it to clear by toggling the Location Services box, so I quit and restarted SCP.
When I did so, it first came up with the bad coordinates, then extremely rapidly zipped through from where it was stuck all the way up to where I was currently, like the coordinates were backlogged and then suddenly flushed out within a few short seconds. More bizarrely, I noticed the same behavior on two other devices (Pixel 3a and Moto One 5G Ace, both on Android 11) and had to do the same thing to those. I also dumped my trails on all three, assuming they were all bad by then. The rest of my devices were correct.
I was barreling down the highway at the time, so I couldn't investigate further. Other than my quoted message above, I've never seen this behavior before, and now it seems to be widespread.