Tom:
Can't imagine a stitch and glue deforming when stored like that. My VKs are stored deck down, hatches off, on a rack under our deck, resting on ntyhe open hatch openings. Lots of rain and snow, ice on the hulls, etc. Haven't come to any harm yet. If stored outside, I think it's better to have the hatches off, or at least propped well off the deck - air circulation is important.