Nought......on short trips.
I carry a buff so use that if have to.
...( BTW, the buff is also a bandage if needs....)
Never carried any sort of towel but on very long trips which didn't involve full time camping, packed a Sarong......multi purpose piece of kit. Large and very lightweight.
Useful for long bus journeys in 3rd world countries when the bus stops on a plain for a loo stop....the guys all turn their backs for a few seconds then turn around and stare at us poor females...SO, out comes the Sarong..."Ha, ha...can't see me now......."
Aye Baldy and back of hand also, don't forget..