Yes it's a (or even the) good method, you have to work in sheet metal to be able to unfold more easily, and add the inserts I think later :o
After that, you still have to pay attention to the scale of the photos, and if you could have the part in your hands to take 2-3 ribs it would be even better!
I think I'm going to take these pieces and lay them flat on a paper, to make the exact contours. Then I'm going to apply the blueprint method, well if I can do it
Why not place the part on graph paper or squared paper according to the size and the ends on the same line, then trace the outline and finally make a survey on the paper. Once the part is made in 3D for inspection, make an ECH 1:1 print from above to put the original on it.