you could claim you are a tourist, swing a couple on the driving range and if you are not inept then they'll let you on the course, but I would not put it past them to
require you to show your plane ticket. A colleague of mine got his platzreife on the same day by simply having straight consistent swings over 160 meters, just in the zone that day. (afterwards he developed a nasty slice)
There is a public golf course (kommunaler Golfplatz ) in Düsseldorf, 9-holes on the Rhine (
GSV), and there you can just drop your money in the basket and go play. You need to fill out the line that asks for your home golf club, just fill in a US club that you know or write 'tourist'. Otherwise, the best bet is simply to sign up for a platzreife exam with the
VcG (club-free golf association). You need to learn the rules
Rule quiz
in German
in
EnglishGood luck.