Hi All,
It's definately not skis - they're to short for an aircraft with that weight and the likelyhood of digging in to the snow when landing, taxying or taking of is great.
A photo of a Storch with skies can be found here
http://www.preservedaxisaircraft.com...i156munich.jpg
I think fuel tanks where generally carried under the fuselage on Storch.
What is of interest to note is that there seem to be an additional strut between the landing gear which is not normally found on the Storch.
Smoke laying equipment is an option but wouldn't that require larger tanks too?
It looks like it has some sort of center line attachment point.