G-raff.I'm having the exact same problem but fortunately I'm heading to a ski camp this week with lots of tramps so its my goal to learn it. Ill make sure to update with vids if I can get close.
Same for me , i don't think that totally legit dub cork 7's on tramp are possible. All the dub 7's i've seen on tramp were actually dub flat 7's(couls also be considered bio , since they are spun quite flat, definetly not rodeo like) , wich is quite close to dub cork 7's. I feel like I could do dub flat 7's but dub cork 7's just seem quite impossible. No matter how hard I'd try to pull into the second cork , i will just always end up as a regular ugly 3.