OK, I pulled the trigger on Copa via UA. The AC penalty sucks (but is a lot less in USD) and I feel like an idiot (not the first time given I am surrounded by mileage experts here), but in the end the penalty is still way cheaper than the positioning flights I was going to book to BOG -- and now I am on a single ticket home with a reputable carrier, so if there are problems I know they'll have to figure out how to get me home. PTY also seems easy. The extra miles are also offset by the savings in extra ticket at least a bit, and are well worth it to make sure my wife and I have zero stress. I don't want to drive her crazy by constantly fretting over this flight for the next few months. Lessons (several) learned here. It is a blessing to only have first world problems.

EDIT: Best part, was able to select seats on UA's website. Quick call today confirmed my reservations, seats, and veg meal request -- with a live, polite, competent human. :-)