I have the Marmot Helium EQ and on my first trip in a tarptent in bad weather, my tarptent lost a stake and collapsed around me allowing about an inch of water to flood my tent.
It was blowing so bad, I dared not exit my tent for fear that it would blow away.
I simply layed on my side and completely cinched up the hood to the size of a blow hole and laid away in the driving rain and howling wind until I passed out from being tired.
I woke up the next morning looking like Han Solo in carbonite with the tarptent plastered on top of me with small puddles of water.
The only part of my thermarest prolite 4 pad that was dry was a 3 inch patch running along the middle where I was sleeping on my side.
My whole bag was soaked on the outside, but I remained warm and dry due to the fact that I had seam sealed my sleeping bag, which was the only thing that saved my bacon!
That said, I survived with nothing more than a blow hole that might have been an inch or two wide....all I know is that I just cinched the hood as tight as I could and bunkered down in my sleeping bag that night.
Winds were strong enough on the ridge that were on that a friend's REI Half Dome bent a pole from being crushed by the wind, forcing him to spend the night in a pit toilet for his shelter....I count myself luckier than him that night.
My advice is that yes, you could do it, but avoid it unless the "stuff" has hit the fan....the condensation build up might warm you up initially, but too much and you probably will start to collapse the loft of your down bag.
Hope that this helps.
P.S. Lesson learned....avoid setting up on a ridge, use large rocks to hold your stakes down, and don't pitch your shelter in a slight depression that turns into a swimming pool.