I want to register a car for a month. What is the best way to go about this?

Rent a car for 20 days. You minimally have to register and insure the car. Registration fees are non-refundable, so you will be out that amount. With insurance you can sign up for it and then cancel it after 20 days, but you will be more more than 20 days worth since they will keep the agents comission. Lastly, why would you want to risk a 20day road trip on a car that gets little to now use? I would want to at least have a few weeks of use on a car so that I can get a feel for it and what may potentially go wrong with it before I take a long trip. You really don't want to be far from home and then have the car fail on you.