Well, I just bit the bullet and did a total cooling system overhaul.
I replaced the radiator, water pump, fan clutch, thermostat, and radiator cap.
Miracle of miracles the problem is solved.
Before I jumped off of the deep end, I did make sure that the headgasket wasn't leaking (internally or externally) and that wasn't any other possible avenues of coolant escape.
It wasn't really that expensive if you weigh it against the cost of replacing an engine from overheating.