It might be easier to create a second profile and PSN account, yes... but it is still possible to back up your save to a USB stick or hard drive or whatever. In fact, it is still very very foolish and reckless not to do so. They should just tell you when you are booting up the game during one of the 16 times it saves before you get a chance to drive "It is highly recommended to make a backup of your save game at least once a week."
I'm not 100% sure, but I think you can also simply copy your save to another profile on the PS3 and use that as a backup as well. You can't play in another profile with the backup, but you can use a profile to hold a backup. This is of course not going to help you if your PS3 dies, so using removable media is still the best way to go.