Update: We drove the thing another 750 miles over the last 6 months (doing a fair amount of towing), and I just got the oil analyzed again. The results were the same, proportionally (i.e. half the mileage, half the potassium, half the sodium, half the copper). The coolant stayed level for a long time, and then all of a sudden dropped probably 3/4 cup or so, but it's kind of hard to tell given temperature fluctuations.
When the coolant level wasn't dropping I was holding out hope there might be something weird going on, but now I'm back to square one. I haven't cleaned the engine or gotten a dye kit yet but that might be the next step. I had been planning to take it back to the shop but might try to do it myself instead to save money. But, there's a lot going on right now and I won't be able to get to it for a little while.
I haven't been able to find much definitive info on what exactly excess copper in a UOA means. What parts are brass/bronze and could be shedding copper? I'm trying to figure out if I can let the wife use the vehicle for its intended purpose or if I should treat it as being out of service until I can get it fixed.
