Insurance and Registration

I own a Class A motorhome. It's currently stored in Pismo Beach, CA. It's registered in CA using a CA address with CA DMV (my fiancé's address). I live in Bradenton, FL. Insurance in FL is $2,400 per year - in CA it's $850 per year. Registration is a bit of a wash except in CA it needs to be "smogged" every 2 years - not particularly an issue.

I'd like to move the motorhome to the East but not FL. South Carolina is my target state. I would store it in SC and use it in SC but I don't have a SC address. Insurance doesn't seem to be an issue with Progressive as they will insure it based on where it resides (SC). However, registering it in SC seems to be an impossibility. Can't register it in Florida unless I pay $200 per month for insurance.

Anyone have any advice, direction, suggestion, re: how I can make this happen?

Thanks.