Duncan, I feel your pain, and I admire you for sharing the truth of it. When people are honest, as you are, it gives us all a chance to learn and become better beekeepers.
I would add one suggestion to your analysis. If you add a box of foundationless frames, be sure to inspect them at least once a week. That way the bees won't have invested too much effort if you need to "correct" their opinion on which way to build the comb. If you can't inspect them weekly, use foundation to restrict their creativity. They can still build brace comb and other undesirable things, but it is much easier to correct.
You can use a simple bee escape on an inner cover for this. The bees usually clear out of the box in 24 hours, providing there is no brood in it.
Thanks again for sharing. I hope you didn't suffer too much from the stings.