I just came back from a 6500km trip around europe myself. My car only had 1800km before the trip so I took it easy at the start although it was quite difficult to restrain myself on the autobahn...haha. RNS510 works and so did my Tomtom. Nice to have when strolling around.
I checked my tyre pressure and compensated for more weight due to luggage. Check oil, first aid kit, reflex vest, reflex triangle, tyre pressure on the reserve tyre. I also did a full waxing and cleaning before the journey. Remember to have travel insurance, tlf number to the VW road service. Passport is not needed but I prefer to bring it with me. Turn off anything that uses data on your phone if it's not needed.
Enjoy the trip!