FYI - the river that parallels 50 near Maysville is the South Arkansas, which doesn't join the Arkansas until east of Salida. The S. Arkansas stays pretty small. It's the Arkansas that gets all the tourists, rafters, and pictures. That doesn't change your conclusion, though. It would be very unlikely to get far on the S. Arkansas, presuming you/something made it past the dam/s somehow. But once you or something were in the main Arkansas, you could go a very long way.
The Arkansas is next to both 285 to the north and 50 to the East, which covers both ways you'd get out of the mountains to go East.
INTERNET/CELL - Probably just satellite that far edit: WEST not east
of Salida. High speed wired internet is not available all the way up the pass, I just can't remember where it ends - I think it ends around the eastern edge of Maysville a few miles from where the M's house is. The "big" part of Maysville. The wired internet carrier is CenturyLink. You can get cell phone service via your home wifi (e.g., Verizon over wifi) so if you are connected to the internet via wifi and someone calls or texts your cell, you get the message just as normal. But cell service away from your wifi is spotty. There are some places that just by experience you know where you can get it, and sometimes it's a surprise. Satellite internet is terrible for things like streaming and gaming, passable for things like YouTube, etc, and decent for just regular web browsing, email, etc.
I'm in the area a lot. No, I don't know the Ms, LE, or anything interesting, I'm just familiar with the geography and some logistics. The case just grabbed my interest because of location.