Purchase automobile insurance on vehicle #1
Make sure you abide by the laws of your state regarding coverage requirements. No specific carrier is recommended. Go with the lowest rate that has the coverage amounts you want.
Include UM/UIM on vehicle #1
In Arizona, insurance carriers have to offer underinsurance and uninsurance to you. If they fail, then coverage is included for the state minimum of $15,000. If you do not want UIM/UM, the insurance carrier is required to have you sign a rejection sheet.
Purchase automobile/motorcycle insurance for the rest of your vehicles
Best to go with a different carrier.
Reject UIM/UM coverage for these vehicles
Remember, UIM/UM from vehicle #1 protects you while riding in/on other cars/motorcycles. You can save money by increasing your UIM/UM on vehicle #1 and rejecting coverage on your other vehicles. This will give you the maximum protection while saving you money.