Yup, that's true. As long as you don't live in Dad's house or operate his vehicle regularly, there is no need for you to be a listed driver on his policy. And you'll be covered if you drive his vehicle, assuming you have his permission of course.
In order to legally drive someone's vehicle in North America, you need three things: 1) A valid licence to operate that vehicle, 2) the vehicle must meet all legal requirements to be on public roads, and c) the owner's permission. If you've got all three things, your legal butt is off the hook. Those first two things are pretty obvious, but many people claim not to know them. And the third thing is extremely obvious, because driving a car without the owner's permission is called theft.
The owner, not the driver, is legally responsible for their vehicle (and any damage it causes) at all times. If your dad says you can drive his truck and an accident happens while you're driving, you didn't just have an accident. He did, because he's the owner and he gave you consent to drive.