This is how we have been taught to pack clothes in a rucksack when we go camping at Scouts.
It works for a single night (in fact, it works even better for a single night), or a 9 day summer camp. It is just as applicable for lightweight camping such as a microadventure, or a family camp.
An extra tip is to put 3 or 4 days of clothes wrapped in this way, into a large Ziploc bag to keep them waterproof.
And no, we don’t put our toothbrushes in our underwear. Yuck!