Guess what? I actually managed to grow some potatoes in those bags. Not very many potatoes, but the above potatoes were grown and harvested last month. So, I am not a complete potato bag failure this time around.
And I still have a second bag waiting to be dug up. I suspect there will be even more tubers in that one. The stalks in bag #2 lasted longer and just wilted last week. I think the key is afternoon shade and infrequent watering.