Final update....hopefully.

Had the head gasket replaced. According to the Mx receipts from the previous owner/s, the head gasket was done previously--but it might not have been done up to snuff. 2 different shops confirmed hydrocarbons in the coolant--so it was a sure thing. Water pump is in pristine condition, which is evidence that it had been changed recently. Biggest question-mark was the head bolts, as the shop indicated that these had apparently stretched. It is not known if these were pushed by head gasket pressure, or if they were faulty previously and not replaced during the last attempt at this repair. It does come with a 12 month 12,000 warranty, so I expect to be driving the piss out of it this summer with the A/C on full blast--just to "stress-test" it to verify that I'm not still getting issues with it. (Hard to tell when I'm doing 15-20m trips and it's 15 F outside).

I'll also be religiously checking my oil levels, as I may now start to see oil consumption (although I noted none previously). What still unsolved is how I got it from SD to Phoenix and finally to SLC without having a catastrophic breakdown.