Back in the day before I knew about convertable pants
I always used the wool arm/leg warmers from my bike touring kit. The arms always stayed up, but the leggings would work their way down in fairly short order, a result of the hiking shorts being loose at the hem rather than tight like cycling shorts. The first time out with them I used safety pins from my repair kit to hold them up; later I sewed on elastic bands around the top and applied some silicone stripes for grip. At the time the light weight was appreciable (215 g); however, comparing them to the zip-off legs of convertables (175 g), not so much. For shoulder season though they can be a useful addition when the temperature can drop 15-20 F in half an hour because of an approaching front and worth the extra weight for the comfort.