Yarn: GGH, Big Easy. Colour: royal blue #18.
At the moment the current solution is to start the ribbed waistband with a yarn of the same size (5-6) and similar colour, which I have found at the Berlin knitting store knit knit. This version of shorts will have to be the Hip version. I will probably knit the high waisted version with another colour... thinking of knitting a burgundy version.
Fingers crossed my solution works!