I take a sit pad. As a back rest, I use a log, rock, tree trunk (check for pitch first!), or my pack propped up with my trekking poles. Works fine for me and weighs a lot less than a chair! For me, the extra weight doesn't justify the marginal (if any) comfort that the chair may provide. YMMV, of course.

The sit pad was also a dog bed at night when I had my dog. Right now it does double duty (instead of triple) as extra padding for my backpack as well as a seat.