I think this problem could be alleviated by having a main character stuck in that hallway with Vader. Maybe a current character could be rewritten to be in that scene, or it could be a new character. The idea is that the audience is hopeful because this character managed to avoid the destruction of Scariff, so we’re rooting for him to get out of there.
B) use him in place of CGI-Tarkin.
I think that could actually work pretty well. It fits with his character to be mistrusting of Imperial officers, so he could be just as antagonistic to Krennic as Tarkin was without it seeming out of place. It would make sense for him to be frustrated in ANH because for the whole of Rogue One he’s been against Krennic, and then Krennic royally fucks up and now he has to clean up the mess.