Sounds like an ordeal. The good news is that these horror stories are rare, although mentioning this isn't much consolation.
JMHO, from what I've read here and the Sprinter forums, they tend to be pretty reliable. The bad news is that when a Sprinter has issues, one ends up paying Mercedes prices to get things back to normal. The Sprinter-source forums has the occasional tale of woe, and when that happens, it is scary.
Nothing wrong with the Ford gasser choice. Finding service availability is one of the best things about the Econolines, not to mention parts. You will definitely miss the lack of a doghouse and the fuel economy of the Sprinter, but getting stranded is less likely with a Ford, and if you do get stranded, a Ford place is likely a lot closer that can fix things, or at least get you jerry rigged enough to make it somewhere.
I can understand tires going at 20K. OEM tires tend to do that. However, the issues that you had at 60k is what someone might encounter at 150-200k, if not more than that.
After getting stranded in Alaska, I'd almost certainly be looking at a trade-in. The rig might work perfectly after that, but why take chances? To boot, with the difference in chassis cost, you will end up with a nice Ford based motorhome.