Hi, Teratophoneus. It's really nice to see this -- I just got a Google alert about it. Just a couple of clarifications.
First, Brontomerus is not "dubious", as that means it can't be diagnosed as separate from other organisms. Although it's represented by pretty sparse material, that material is well diagnosed and obviously distinct.
Second, Camarasauromorpha is not really as "tribe" of Macronaria -- it's pretty much the entire clade, in fact it's questionable whether it even deserves its own name. It includes everything inside the tree rooted at the most recent common ancestor of Camarasaurus and titanosaurs. So in saying Brontomerus is probably a camarasauromorph, we were not saying much more than that it's likely a macronarian. Although we note (p89) that only one additional step is required for it to resolve as a basal diplodocoid or a non-neosauropod. So while it's diagnosable, it's very uncertain as to phylogenetic position.
(Because of this, guesses about things like neck-length really are whistling in the dark. We use Scott's Camarasaurus as the basis for our skeletal figure not because we're convinced Brontomerus was very similar, but just because Cam is sort of the vanilla macronarian that all other specialise from.)
Third, I was a bit surprised not to see a much beefier thigh, since that's the one thing that we do pretty much know about this animals!
Anyway very nice work; and it's always nice to see my baby get some attention.