I agree with others: If I have clean underwear and socks, I'm happy. I just wear outer clothes in rotation. Saves a lot of room in the duffle bag. Wife does similar.
Another thing we do is bring two pairs of shoes/boots. Alternating shoes every day or so makes me feel better.
Never been gone for more than 10 days on a trip, but if I did, I'd just bring all my synthetic Tees and hiking pants and wash them in a sink. Or find a laundromat with a bar next door.