mich800,
You are completely wrong that "you can't do that in Michigan anymore". Just did storage only on an SUV on Jan 2nd 2020 with our Michigan based insurance policy and off storage coverage only on March 26th 2020. All done thru our insurance agent and was over the cellphone when we left for Florida and on full coverage on the return trip. Have done it for boocoo years and it works just fine. We specified the dates for on storage and when back off on 1/2/20. Wife cashed the rebate check at our bank wirelessly on her cellphone.
Have the documents to prove it so we know it's a fact! Maybe you need a different agent or ins company?