Consider that UA puts the F lavs near the cockpit door on the domestic 777s, so those can stay, which would allow for the removal of the 'stink-shield' lav in place of 1AB. Behind 5KL is a rather large closet and wheelchair accessible lav, both of which can probably be removed (replaced with a standard lav) to create 6KL. One (or both) galley units at the 2L/R crossaisle can be removed and replaced with a closet, lav, seats, or any combination thereof. Domestic-style service to beach markets likely do not require the same galley or closet space as typical longhaul international flights.

The two lavs at the back of A-zone in the sCO configuration would remain for Y pax. Aft of there, I'm not sure what they would do, but I imagine a 3-3-3 configuration would be installed as well.

I don't think it's out of the question.