Vehicle Import Germany from Switzerland

Hello to each other, I have tortured the Internet, but I didn’t really find it. It’s about the import of a Swiss vehicle to Germany. It’s a classic car (33 years old) originally from Germany (Mercedes). I know that I have to tax or customs the car. It’s either 19% EUSt or 7% inch if the car is recognized as a classic car. So far so clear. This information is actually everywhere. But what now? Mostly becomes on “professionally” ” Importers/brokers are expelled, but is this so difficult to carry out themselves? Planned border crossing is Kreuzlingen/Konstanz on the A7/B33. For my understanding, I use the ATLAS page for an Internet customs declaration and fill it out as far as possible and use the tariff number 9705 for vintage cars. Actually also clear. But what do I have to do on the Swiss side? Is there anything for the export? Export registration marks at the office in Switzerland should, however, not be a problem, that is on the en I wanted to get a confirmation from the TÜV that the vehicle will most probably receive an H-mark in order to provide an argument for the tariff number.