A big full sleeping bag has always seemed to me like something to have near my BOB, but not in it. It simply takes up too much room. One of the fleece sleepng bag liners might be just fine for sleeping indoors almost anywhere. I've thought about, but never tried, putting a liner inside a heatsheets bivy. Not too durable, but it could really expand where you could spend a night.

My most space efficient jackets are a combination of soemthing like the anorak you mention and a thin fleece. Either alone can be fine at a lot of temperatures, and together, I've feel pretty good even when it is below freezing. So, I would add it, if cold weather might be enountered.

If cold weather is possible, I am big on layering.

With both of these, do you still need the cheap poncho? The anorak should take care of much that the poncho would.

I'd add a P38 or P51 can opener, as it would give you something like a blade. TSA inspectors and officers at courthouses have both let me carry them without saying anything. I've been tempted to sharpen mine, but have not, although it is secured with tape.

Consider a cheap inflatable pool float patches. It would take up little more room than a poncho, but it would give you soemthing that might be serviceable as a mattress for a night. I'd rather have a real sleeping pad, but that takes more room. A patch kit might be good too.

Aspirin, tylenol, etc. Bad or strange sleeping accomodations can lead to sore joints and muscles.