Suggestion-- 10 or more feet of caution tape rolled up tightly or wrapped around a card of some sort for signalling.
A non-sticky trail marking tape about 1 in wide and blaze or hunter orange. Cut into 3 equal lengths, tie equidistant on a long stick and hold as if a flag or banner.
Or tie a length of twine to a rock and also tie length of tape to said rock, hoding empty end of twine, twirl in such a way as to create an airborne circle.
Doesn't take up much space.