Fair question ... I wear under shorts, zip-off shorts, t shirt, short-sleeved shirt. I pack the same. One pair under shorts, one zip-off shorts (with the legs - two shorts one pair of legs), one t shirt, one short-sleeved shirt. That is the stuff I wash, not much, and not often either and I still smell sweet (possibly).
I wear Keen Newport sandals so no socks (and no blisters
).
Thing is - you can only wear one item at a time and the other item is either in the pack clean or on the line drying - why take anything else? Why carry the weight of clothing you don't need?
I use my body soap to launder (in the shower) and occasionally washing-up liquid if there is some spare in the refugio kitchen.
I don't wash clothing too often, nothing wrong with a little trail dust on shorts and shirt! - Mind you, clothing on my skin is cotton - takes days to even begin to smell - but if you wear that ghastly 'tech' synthetic clothing you will be washing them all the time as they stink really quickly.
As well as the 'spare' clothing I take outer wear ... Musto windbreaker fleece type thing and rain top ..... as I am going to Camino tomorrow and there will be a week of 10 to12C during the day and about 2C at night - so 4 to 5C in the walking morning - I am also taking a back up pair of socks in case my toes get a little cold and a long-sleeved thermal t shirt and an old sweater. Both are really old and worn so I will dump them when the weather improves into real spring.
Thing is, especially with women, there seems to be an overkill on this laundry thing ... it is ok to look dusty, or wrinkled, or slightly sweaty ... it isn't a first date or a meeting with the Queen ... so be cool, become a little wild - and just take one of each that you wear during the day in your pack.