DD:
When you are first setting it up you might expect a few questions and some confusion from the insurance company. Usually after a few phone calls and letters they get it and do what you need. I had one car that has variously been registered in Massachusetts, North Carolina, Nevada, Utah, Florida, and finally California.
I had that car in California for one year in 91/92 and didn't register it there. I got a job with a company in Nevada at the end of the year and used a friend's address to register it in Nevada as my NC reg was about to expire. About 9 months after that I registered it in Utah. A short while later I get a letter from California saying they have a picture of my car in Sacramento with a Nevada license and that I was responsible for all sorts of fees and taxes. At that time they were really going after people who registered cars in Nevada but lived in California. I responded that, not only do I not live in California, I don't live in Nevada either and the car is now registered in Utah. Seeing they didn't have any case, the issue was dropped.
A few years later that same car was moved back to California where I did live for a time and did register it. When I moved from California to North Carolina again, the car stayed in California. I was looking for a new insurance company at the time. I called Geico and was explaining the whole set-up to them and they just couldn't get it. At some point I said something about not living in their perfect little cookie cutter world and the lady just hung up on me. Eventually I got an insurance company that could reliably keep cars insured in more than one state, but as said above I had to give them a permanent address to base it from.
Typhoonpilot