Re-lasting update. My loafers came in. They look great. The fit is OK. Just a little loose, but wearable. I had a choice between a "D" and a "B" width. I went with the "D". A "C" would be just right I think. Keep an eye out. They should be easy to spot at the airport.
UPS and FedEx will add a broker fee (for handling the paperwork) even when there is no duty owed on the imported goods. Whenever possible, I have the goods shipped by the postal service (Royal Mail etc.). The US Postal Service handles the delivery on our side, and they have never charged me a broker fee only the actual duties owed. Hope this helps.
At the risk of being repetitive, I suggest reviewing the Brannock fitting instructions here.
And don't be shy, ask the SA what he is measuring and ask for a comparison between the heel-to-toe and heel-to-ball measurements. It may save you some trouble.