Sounds to me like y'all could use a bigger door on the warming tent if it took ten minutes to get everyone inside. Such events demand a no-waiting sort of accommodating architecture.

Best organized Polar Bear dip I've seen had a large tent, kept at about 80F with kerosene fed jet heaters, all of thirty seconds away from the water.

On the other hand avoiding hypothermia entirely would have deprived you of a valuable experience. Unless someone has experienced it it is hard to comprehend how even simple things can become near about impossible when your hypothermic. How holding a match can be a two-handed job.

The biggest revelation for me was just how profoundly it can effect the mind. How it can make just remembering what your doing, what your supposed to be doing, difficult. People joke about how they wanted to dial 911 but couldn't remember the phone number. Or how they can't remember if the red, or the black, cable hook to the negative terminal. Stuff you have mastered since you were six; your suddenly not sure of.

Hypothermia, and sleep deprivation, are the reason you seemingly brainless three item lists being used. Why the military usually sends two or three people at a time to do even simple jobs. One guy reads the list, one guy gives follows directions, and the third makes sure they stay on mission.

It is important to plan ahead and set things up and anticipate so you don't become too hypothermic to function, or remember what you have to do to survive. You set up the tent and heat up the tea before you get hypothermic. Imagine if your belated warming had been the beginning of your adventure. You fall in, get chilled and wet, and then drag yourself ashore on the verge of hypothermia with no warming tent in sight. You have a couple of minutes to build your own warming station. First prize - you live. Second prize - they find your body when the snow melts.