Hi Clark. Thanks for the photos. Now that's a strange one, for sure. Hmmmm....?
I can't quite make out what fin system it has (should be a Waveset). Does the base of the fin have a screw on each end of it, or one screw in the back? Do you have a picture of the fin/fin area, by any chance?
As the lam says on it, it's a Custom Design model, which means it's not quite the same as any of the standard Bing models that were offered at that time. This was a time of a lot of experimentation and people could order whatever they wanted. Most of the Custom Designs I've seen are either guns, mini-guns, eggs, or short longboards, and all of them were made in spring/summer 1968.
Yours is really not that much like a Vincent, which it preceded by a few weeks, other than maybe its outline - it's way too thick in the tail; the rail is pulled up in the tail, instead of 50-50 or slightly down railed; it has a V shaped bottom, instead of a flat bottom in the tail section, and; it's square-tailed, instead of a diamond. All these feature are similar to the Australian "V" Bottom model, though the tail looks too narrow on yours (V-bottoms were 19 inches wide in the tail!). The tail width on your board looks more like that of a Vincent, maybe the nose too. Can you tell me how wide the nose and tail are? Measure across, 12 inches back from the nose tip and 12 inches up from the tail end. Also, if you haven't already, please tell me how long it is (looks very short). I can tell you how its dimensions compare to the Vincent once I hear back from you.
I don't think it's something Bing would have shaped. Mike Eaton probably shaped it. I'll forward your pictures to Bing.