Max, Seeing nobody picked up on this... And, with the understanding, I am in pretty much the same position as you... From what I have learned over the months: some will say; a very short mast* will allow you to 'taxi' in calm water without the prospect of 'blowing up' every 60sec. and allowing you to continually test taking off and landing. Another said: a shorter mast is fine for calmer waters.
Yet, if I remember the latest on this topic from Patrice at GONG. The longer the better. It keeps you up and away from surface interference. I am assuming the expected beginner oscillations are more tolerated. (it came in an email promotion but I was unable to find the quote.)
Jim
*Slingshot had a 12" (45cm) mast they called the 'Taxi mast'.