There are some things we need to consider here. First, insurance rates can vary daily so you can really only shop for and purchase insurance a few weeks before you will need to use it. Second, if you are traveling to different states and renting a car at each location, you will not be able to purchase a policy. Insurance is state specific so there is not a policy that will allow you to continually drive different cars in different sates if you do not have a permanent location. You would need to be driving in one state for 10 months out of the year. Unfortunately, you will need to pay for insurance through the rental company. Since you are from out of the country, check out our guide to car insurance for foreigners
and we can help you find the cheapest rate.