Bob,
I hadn't thought of dark morph Ferruginous Hawk as an option. It's certainly interesting, but I still think the bird in the picture is a young Bald Eagle.
Looking at pictures of Ferruginous, it seems to me that the yellow gape line contrasts more with the head color than on this bird. Also, although Ferruginous does have a large bill, none of the pictures I looked at showed Ferruginous having such a big bill in proportion to the head size.
Unfortunately I don't have the Wheeler guide (potential Christmas gift, perhaps!), so I can't compare directly with the photos you mentioned.