You will need an address for:
Tax Filing
Auto Insurance
Vehicle Registration
Medical/Health Insurance
Banking
Voter Registration
other things that I've forgotten.
As mentioned above there are many companies that provide mail forwarding service. The majority of full timers use either Texas, Florida or South Dakota as their state of legal residence.
Best advice I can give you is once you do your research and pick a service and address that meets your needs, then use it for EVERYTHING. Don't try to cherry pick the best rates and costs by using one address for one thing and another address for another item. It is too confusing and can lead to too many questions about whether your intent was to be a "fulltimer" or if your intent was to evade/avoid paying taxes.