IIRC you can get a basic AAA membership for something like $40, which seems a pretty small expense for the number of maps they can give you and a pretty small expense when looking at a coast-to-coast tour. I don't know if things like the towing services would apply to bikes but if so it would at least give you some options if you were to break your bike and not be able to fix it (from what I recall the cheapest membership option only provides for a 5-mile tow, so it may be of limited use)

As an added benefit if you're expecting to pay for overnight accommodation anywhere along the tour you may find the AAA membership pays for itself in the form of discounts. I took an AAA Plus membership to cover an 8-week trip to the US which cost something like $120 and paid for itself within the 8 weeks I was there.