Hi Andreas -- Sorry for the delay in answering your question.
The German set up adjustments should not result in overstacking. Instruction 2B on Card ISS A should list hex 0703 for the 12SS division, not 0803. We will add this correction to the addenda.
Great! Excellent game by the way! With a toddler back home soloing is the only way to get some gaming going nowadays. I've therefore gone on a Butterfield shopping spree lately.