Here are the ground rules I am setting out for myself:
I will not count among my 11 items my trail runners, light wool socks and liners, synthetic boxer shorts, shirt, bandana, eyeglasses, or convertible pants, which I wear at all times when I'm hiking. I will not count the food I bring to eat. I am assuming I will not be attempting to cross any terrain where the risk of injury is high, such as talus slopes or steep snowfields. I am assuming no worse weather than heavy rain, or a clear, cold night not dipping below my sleeping bag's rating.
Now, in the spirit of producing the most minimalist and UL-inspired list I know how to put together (that I would actually be willing to attempt) this would be my list:
1. frameless backpack with hip belt
2. 20 degree-rated down sleeping bag
3. 76" x 20" closed cell foam pad
4. single-walled, freestanding tent
5. two-liter platypus water bottle
6. gravity-feed water filter
7. bear can
8. rain jacket with hood
9. rain pants
10. waterproof dry bag for my sleeping bag
11. topographical map
Here are some explanations of my choices.
I would not cook my food, eliminating the need for a stove, a pot, or any other utensils. Non-cooked food is almost invariably finger food. This also opened up the possibility to eliminate a lighter or matches, which economizes on the number of small-fry items, which add up fast if you don't watch out. Eleven items is extremely hard to stick to.
For water, I chose a two-liter platypus so I'd have sufficient capacity I could walk away from a water source to spend the night, if that served my needs best. Water-born disease is not common in the wilderness, but it is the last thing you want to deal with when you've cut your gear down to 11 items, hence the water filter.
By choosing a single-walled freestanding tent I adroitly sidestep any arguments about whether stakes or a rain fly are separate items and I also minimize the necessity of staking the tent. In a windy situation I'd just have to anchor it with rocks, unless stakes are allowed me as part of the tent.
I tend to think preserving body heat is the most reliable way to stay warm. My sleeping bag is a hugely important piece of my safety equipment. That's why it gets its own dry-bag. The closed cell foam pad would provide decent R-value under me and be used to give some structure to the frameless pack, this being UL SOP. My backpack would probably have to double as my pillow, maybe wrapping it in my rain jacket, if the jacket is dry.
The rain jacket and pants are the most versatile items of extra clothes I could identify. They cut the wind and preserve warmth well. They can even be used in camp if the bugs are horrible. And in rain they would allow me to stay somewhat dry. A hood can keep your head warm and comes as a bonus with most rain jackets. If it is colder than the rain clothes can handle, I need to get into the sleeping bag pronto.
In cutting out most little bits and pieces of gear and safety items we all usually carry, I privileged staying warm, dry, and hydrated as 8 of my 11 items. The remaining three are: backpack, bear can and topo map. The backpack is self-evident and probably ought not even count as an item. A bear can is unarguably a single item and not losing my food in this situation is paramount. The topo map is the best insurance I could have for staying found whether I am on or off-trail.
Anyway, that's the sort of thinking that's behind my list.