easy way to get six star wanted level

You have to unlock that abandone tower at pilot school first, then steal a lot of rhino and store at abandome tower garage, finish pilot school, take the rhino from military base and keep shooting the rhino you store in your garage , and come out of the garage and shoot rustler ,hydra,helicopter cargo. The plane might spawn again, just keep shoot them and come back then go away then shoot them and repeat the whole thing until get six star.