I would prefer not to dig into TFA for Phasma. I’d either leave every beat of her in TLJ or remove her altogether.
As I think about the potential of the deleted scenes… assuming they are usable and presented nicely, that might be the single biggest aid to the film. I think TLJ would have been a superior film if it were presented as a 3-hour Star Wars film and ask the audience to just accept this, rather than both packed to the brim and cut to the bone. Of course, we’ll have to see how it goes, but I hope to give it a running time as merited, not out of concerns of marketability.
But still maintain all of Canto Bight. Why not significantly trim that sequence and then just add the deleted scenes relating to the interesting characters/stories. Would probably end up being a similar runtime but be more focused on the more interesting and substantial plot lines.