I use a small self-inflating trail seat. There are lots of options for those in the market. They pack up small and tuck away fast. I keep it in a cargo pocket of my hunting pants and every time I stop for a sit, be it on the ground, log or rock, a few breaths in addition to its own action inflates it in seconds.
On days I plan to glass for extended periods, I carry a lightweight stool, usually in conjunction with the trail seat. It’s far more forgiving on the body and I think makes it easier to keep your eye in the glass for extended periods with little weight penalty.
I have used the REI inflatable with good luck in AK and the cold. Currently using the Klymit V-seat due to being 2.6oz, but unsure if I will just cut my foam thermarest and use that for the extra width which is the downfall of the inflatable klymit.
I cut a 72" thermarest z-pad in half giving me 2 36" pads. I use a 36" as a seat and as a second layer (over a 72") for my torso when sleeping. The 36" can be used full length if on snow/wet stuff or doubled up for more padding. 36" is also long enough for an overnight pad in an emergency, depending on your height.