I couldn’t tell you how many, but in a guest blog here on BL in 2010, Enns said, "The various flood stories simply share common ways of speaking about a horrible flood of some sort. It is a common scholarly view that either a severe local flood (around 2900 B.C.) or numerous local floods triggered these flood stories. Most biblical scholars understand these ancient stories as attempts to explain why such a thing could happen. The answer: the gods were angry."
I wasn’t necessarily disagreeing with you, just letting Walton speak for himself a bit. Evangelicals do have an allergic reaction every time they hear the word “myth,” no matter how well the term might or might not fit Gen. 1-11.
Either way, interpreting a myth as “disguised history” is not illegitimate. (There is a very good synopsis of various methods of interpreting mythology at this link to an undergrad course on world mythology.) In a nutshell, interpreters in the modern era may agree that there was a historical Troy and probably a king named Gilgamesh (not Noah), but the value of such knowledge is limited. It tells us nothing of how the original audience understood the story, let alone how we should interpret it today.
“Hyperbole,” in this case, is sort of like the label “based on a true story” that appears before a movie. The main character might have the same name as the real person, the natural disaster at the center of the plot might have happened, but the rest may bear little or no resemblance to actual events.
@TedDavis and @Joel_Duff probably can speak to this better than me, but for a little historical perspective, in 1872 George Smith presented his translation of the 11th tablet of the Gilgamesh epic, “The Chaldean Account of the Deluge,” and the immediate reaction was that this discovery had confirmed the biblical account of the flood and the historical truth of Genesis. Of course, eight years later when he published his translation of the full epic under the title “The Chaldean Account of Genesis,” the public reception was less enthusiastic.