I like 35lb better than 40 but it's hard to be comfortable at altitude for the night with much less. (35lb each for 2 guys sharing gear)
Have considered poncho-as-tent on many occasions but on just as many occasions the hail or thick mosquito clouds caused me to un-consider.

For solo dayhikes off trail my just-in-case is about 25lb.
Hiking back to the car in a snowstorm confirmed that was about the right amount of just-in-case.