hahahaha oh my god, those photos are TERRIFYING. if you ride near those trucks in the snow, i shouldn't be so afraid of riding my highway on frosty mornings! good god!
i love the last picture, even if it does look a little indecent. hehe.
my bike is a bianchi milano and you have an excellent memory.
i just took really, reeeally rough measurements and in the back i think there's about 2" between stays where the tire is, and in the front i have more room, with between .5 and .75" to each side of my 1.5" tire. it's hard to say because there's lots of stuff in the way of my measuring. hey i actually have mtb tires from my sister's bike that i could try on my bike! then i'd have a better idea. and like you say, i can always get different fenders, which wouldn't be a big deal (i don't think).
so just to clarify because i'm not totally sure, do you think i need the extreme tires if i ride on thinner, flat ice, and many or most mornings there's no ice at all? if we get heavy ice or a decent amount of snow, everything shuts down and i don't have to go to work