11:41 a.m. on September 22, 2012 (EDT)
ppine said:
I am definitely "suggesting that we live in lean-tos, don buckskins, and invite large dogs, and use animal furs." The old ways are the best ways.
You left out the key words "for you" in the statement above. Once again it is impossible to suggest what is the best approach for another individual when you are:
- not that individual
- not frequenting the exact area
- not subjecting yourself to the exact conditions that the op is going to experience in that area
Another question I have is how effective is a lean-to when one does not have the ability to make a fire because everything is soaked from days of previous rain?
In a scenario such as this you would lose the ability to have the shelter reflect heat back to you.
This is what works "for me."

Now mind you no snow was in the weather report when I arrived for this trip. A ranger pulled up when I was getting dropped off and told me there was a pretty good "surprise" storm moving in. He asked if I was prepared for it and I told I should be fine. The ground was bare, everything was wet and there was minimal wind(as seen below.)

I would refer to it as more of a breeze if anything.
Well as the night progressed the winds picked up dramatically, temps plummeted, and the snow came.
If you look closely at the first picture(the next morning after my arrival) you will not only notice the snow on the sidewall of the outer tent but the build up near the base of the tent on that end as well.
This was caused by the wind blowing from that direction.
So with that being said. What would I have done at 3am in a lean-to if my shelter was pitched in the wrong direction? Ate spindrift sandwiches for the remainder of the evening then woke up to looking like Frosty the Snowman? Got up at 3am and repitched my shelter to negate the wind?
The snow came down for the next few days:

(horizontal snowfall anyone?)

You say "the old ways are the best ways?"
Sorry, but I have to 100% disagree with that statement.
It might very well be the best way for you but I am going to go out on a limb and say it is not the best approach for everyone.
As Ed stated above:
"Mankind may have been using certain shelter systems for millennia, but there is a reason why we have created alternatives – mostly to obtain a better shelter solution."
(On a side note I would also like to point out that the inside of my tent is typically 15-20 degrees warmer than the outside when buttoned up. It is a solo tent and holds the heat that my body generates a bit.)
The amount of heat one finds in a shelter will be dependent upon how large the shelter is and how many bodies are in said shelter.
If I was solo in say a 3 man tent the heat generated by my body would not heat the interior of the tent as well because there is a much larger area of interior volume compared to a tent such as my one person shelter.
The only heat source I have at night is myself. My sleeping bag(here) does not provide heat. It just retains the heat my body generates and insulates me.
Now some may say that a tent retaining heat is no big deal. Well, from my own personal experiences for me it is.
W/o an external heat source(ie a fire) there really isn't much benefit to a lean-to in harsh conditions other than overhead protection when one accounts for changing weather patterns, shifting winds, horizontal rain, sleet, so on and so forth.
On a typical lean-to set there are 3 open voids which equates to 3 different ways nasty weather can effect not only me but also the gear I am using.
So this gives me a 1 in 4(25%) chance of getting it right for the weather I may or may not encounter for the remainder of my slumber/trip.
Of course one could account for this a bit dependent upon pitch(implementing sidewalls into the pitch.)
On the flipside it doesn't matter how I pitch my tent being I am fully covered from every direction.
(I have used a lean-to shelter in milder conditions on quite a few occasions over the years btw.)
Remember, Mother Nature could care less who you are or what gear you have.
When meandering around the bc you are at her mercy.
If you are out there enough you will realize that she typically shows none when you are lacking something gear wise that you actually need or when you are unprepared for the conditions you may encounter.