I asked Slingshot Germany (info@slingshotsports.de) and US (info@slingshotsports.com).
Slingshot Germany: that guy told me, he is also 68 kg and his first board was a wizard 105 and that the foil is more decisive

Slingshot US: "Typically the Wizard 105L was not designed to be used as a beginner board for windfoiling. We believe more volume will help learn the basics and progress windfoiling quicker, making for a better experience overall.
"
This guy seems did not start with the 105

5 years in Switzerland and Schweizerdeutsch is still a challenge. But I got you PatK:)
Going to see/buy that foil and board tomorrow. I`ll decide about the board when I see the board.
Thanks all (including Slingshot)