A guy wearing a skirt (or nylons without long pants), yeah I'd definitely say that's crossdressing in the modern world. I'm into dress-switching myself (on the boards here I'm a female bondage sub) and like the feel of a skirt, but I wouldn't want/dare to be seen in open daylight on the town wearing a knee-length skirt, though it fits my figure (and I seldom wear one without "enhancing" my looks a bit: make-up, breast filling etc). I never tried mini-skirts or printed dresses. Pants (trousers) have ceased to be a gender marker of any kind.

It's interesting you have an army background though that was before any acquaintance with BDSM? The folks there wouldn't have accepted it of course. Skirts are very different, move differently and profile your figure in other ways than pants. The mental and social barrier is still very high but I think it's eroding, at least in the big cities. Some recent types of wide boxer shorts are not that different from skirts in contour and it might be that within five or ten years the acceptance of men wearing skirts (contoured skirts, not kilts) will be stronger than it is today.