Do you know about your phone's mobile hotspot?
There have been a few posts in various threads here that I read and thought "mobile hotspot would make this work." I'm guessing a lot of people haven't used it. Rather than derail other threads, here's a new one about this specifically.
If you have reception, your phone can create a wifi network. You can turn it on and off at will. If you have a decent phone and plan, it can be pretty fast. (Mine is fast enough to do video meetings and remote desktop.) It's not a solution, it's more like a workaround. It drains your phone's battery when in use, and your carrier only gives you so much data this way. But routes and activity recordings are small. It's the same as any other wifi network, your head unit should have no trouble with it.
I've seen posts about some head units will only do some things over wifi (update maps, download routes, update firmware, etc). I've read criticism of one head unit, saying it's bad for touring because WiFi is seldom available and BT is always there.
So, I want to make sure everybody knows this is probably already in your tool bag.