Another reference work on Romans 9:5 worth considering is Gordon Fee - Pauline Christology: An Exegetical-Theological Study (Peabody: Hendrickson, 2007 pp 272-277). Fee is not as fashionable as the authors mentioned in your study, and does not have the same approach. Nevertheless, this is an acclaimed work by an outstanding NT scholar. I also happen to agree with him! In a review of Fee’s book on Evangelion, Don Garlington says:
Readers may be surprised that in the two places in his letters where Paul appears explicitly to call Christ God, Rom 9:5 and Titus 2:13, Fee denies that such is the case. As regards the former, Fee concludes: “It seems incongruous both to the letter as a whole and to the present context in particular—not to mention Paul’s usage throughout the corpus—that Paul should suddenly call the Messiah theos when his coming in the flesh is the ultimate expression of what God is doing in the world” (277). Don Garlington - Evangelion
Fee’s interpretation is very detailed and densely argued, referring to the three interpretations as outlined in your post. The section needs to be read in full, but he comes to the following summary (my apologies for the absence of pointing):
My point, then, is that the presence of the ων is ultimately irrelevant in terms of meaning but its occurrence is almost certainly responsible for the present word order. Had Paul chosen to emphasize only that God should be blessed forever, then none of this discussion would have happened, because there would have been no ων επì πάντον.But since the emphasis is on God’s being the ultimate source and ruler of “all things,” especially the glorious history of his people, the word order comes out the way it does. It seems incongruous both to the letter as a whole and to the present context in particular—not to mention Paul’s usage throughout the corpus—that Paul should suddenly call the Messiah θεος when his coming in the flesh is the ultimate expression of what God is doing in the world.
(To make complete sense of this, the whole passage needs to be read, which it can be here).
The fact that Titus 2:13, which seems to say something similar to Romans 9:5, is brought into the argument seems to me significant.