As I think on it, I anticipate removing Phasma from TLJ altogether. The film is overstuffed, and Phasma already had a plausible “out” in TFA. She was not necessary to the story of TLJ at all, and cutting her material allows for a much easier removal of some problematic Finn, Rose, and BB8 stuff.
It will depend on whether it can be pulled off. I’m pretty sure it would require some visual FX work to remove her from several shots, since she is present for an extended scene as DJ sells out the Resistance and Finn and Rose are prepared for execution.If it’s doable, this is what I’d prefer, but I am far from certain it would be.
I had an idea similar to this on the TLJ ides thread. You could cut out all of Finn and Rose’s scenes after their capture (or lightspeed kamikaze). Their fates would be undisclosed until they arrive at Crait, so we’d be in Poe’s POV. Not only would this cut out questionable scenes, it would also have an emotional impact on the audience (who think they are dead or still captured).
The only problem with this is Phasma appearing right when they’re captured. You could dub Phasma to a male voice and imply this is another, male captain. There’s got to be more than just one captain in the First Order. You could even recolor the red strap blue.