Registration and Sales Tax
Gene, here are a couple of guidelines I''d suggest you follow...
1. Do NOT register it in CA until the boat returns to CA. They will assess you an annual personal property tax and, each year, you will have to seek a cancellation of the assessment. Better to avoid the hassle in the first place.
2. Each state does their sales & use taxes slightly different. With some time before you must commit, why not talk with a local (county, most likely) tax assessor in each State? Spell out your plans & sked, which after all are a bit unique, and ask them how their law will apply to your circumstances. Imagine a sequence of when the boat will be where (within the U.S.) as part of the picture you give them. Follow up with Q''s that seem relevant, based on their answers. Then sit back and assess options and risks.
I see this topic on BB''s all the time and RARELY has someone approached the people who, ultimately, have the answers. Asking for info isn''t the same as commiting to it, so why not start there? I''ve done this in CA, MD, FL, NC and VA and have yet to find an office that didn''t have the basic rules in a brochure, answered all my questions, and left me with my options. Seems like that would suit your needs, as well.