Split the ninth.
I agree.
The 9th should be California, Nevada and Arizona (currently, 29 justices, 7 vacancies). Should be reduced to 18 justices
The 14th (new) should be Hawaii, Alaska, Washington, Oregon, Idaho, Montana and pacific islands. Should also be 18 justices.
Would recommend making the headquarters in Anchorage AL till the new court house is built in Portland. Then assign 10 or so justices (oldest) from the 9th to the 14th. They will not want to spend 2 years in AL so the older ones will retire. That should open up about 8 slots, leaving about 16 justices from a requirement of 32. Lots of opportunity for President Trump to fill those slots.
Just thinking out loud and speculating.
A change in nine prevents more crime.
Dissolve the ninth, retire the number, and establish three different circuits from the geographical area.