Chuck,
The Basque bowyer I told you about (Asiertxu), made his bow much like an ELB, but with a rounded belly - slightly flattened is what he said, not the high crown as in a true Yew ELB. I described the properties of Buckthorn being very like Yew. So much so that he called it "poor man's yew". I'd give that design a try. If you mess it up it's not like there isn't tons of the invasive stuff around to try making some more bows out of.
Matt