you know, I think I was doing that, but that day was a drag from all regards. I mistakenly was slightly underdressed thinking it was going to be a bit warmer (was in the shadow of a ridge for a while, so was colder, and there was a wind too out in the open sections), I was skiing with a guy I'd never skiied with before-he was a stronger skier than I but kept up at his speed more from a losing face sort of thing; then I couldnt drink....so all in all was rather cold, dehydrated and kinda dopey and never really recovered---all that to say that I remember all the negative stuff and so even if I wasnt doing the "blowing stuff back tube thing" correctly, I really dont have the urge to try a camelback again for a longer xc ski at -10 or -15c.

I could see how experimenting with the bladder and pipe being under clothing could work, and just trying diff techniques for a given temp too. For the type of skiing I do with family or friends, the time to stop to open a nalgene isnt an issue, or a sip of hot chocolate or tea from a small thermos either.

I could tho how a camelback would be handy for someone really wanting to make time and such.