The lack of good photos is probably why no skinner has ever made a skin for the flakpanzers. There were not many made and they were not used for long relative to other German GVs.
For me it is a month or more of work to create the first skin for a subject, doing all the panel lines, fasteners, textures, shadows, weathering etc. However most of this work gets carried over to subsequent skins. It usually takes me just a few days to change the colour scheme and some of the weathering to create another skin from the original template. So for it to be worth doing the initial work involved creating a new template there needs to be a good variety of other skins I can use it for later on and there just isn't with the flakpanzers.