It's a matter of practice. 500 km is 312.5 miles. At 60 mph, this is about 5 hours of driving. You can definitely handle 5 hours of driving at one shot. Start at a time when you don't expect to feel sleepy for the next 5 hours and you'll be set.

No, it isn't. It's the difference between driving in the EU and driving in N America.

I can't think of any 500 km route in Europe that wouldn't destroy me. And a little engine screaming for dear life wouldn't help

no it's not. that's 4 hours of highway driving. waking up and starting a drive at 6am and driving until 10am is not any more dangerous than normal short trips and in fact is probably safer since you aren't dealing with intersections.