I have nothing to back this up, but my gut instinct is to tell you that insulation only slows heat transfer, it doesn't stop it completely. Unless you're pouring beers pretty much continuously those lines are eventually going to freeze up on you.
If you want them up high, I'd just mount them as high as you can on the fridge door and call it good enough. I'm sure there are ways you could run them through the freezer and make it work, but it would probably add considerable expense and effort.
Plus that just seems too high to me, but that's a matter of personal preference.