Existing museum birds are there for LIDAR scanning, including a YF-12A at the AFM, so it is possible to get good data.
BTW there was a heated debate on another board about a bulged aft belly that did or did not exist on the A-11/SR-71/YF-12A, and the “no bulge, any variant, any time, anywhere, no way, no how” camp seemed to win because they shouted the loudest. BUT! I personally walked under the AFM’s YF-12A and it DID have a bulge in the back, with a noticeable kink in the lower fuselage contour. Shows how much the bully expert crowd knows.