I'm curious to know what size duffel bag you're using for about a week's worth of clothes. Also, do you have any specific recommendations?
Why do you need a duffel bag? A plastic trash bag works just as well. It is lighter, easier to handle...
Don't take a bottle of shampoo and a bottle of bath soap. Just take the shampoo; wash your hair and your body with shampoo. I get this at Sam's Club. Couple of tablespoons will wash the hair and whole body and the wash cloth will still be sudsy.
Honestly just find one that fits your clothes you're going to put in it. Different clothes take up different amounts of space. I basically own and wear 0 shorts. All canvas pants. They take up significantly more room than basketball shorts. Get what you need. Not what others need.
Rothco parachute bag - Large. I stay out 3-6 weeks at a time. I can fit 7 days of clothes. I can squeeze a bottle of shampoo in as well, just make sure you wrap it up in something waterproof in case it opens. This bag also comes in small if you want to bring toiletries and other odds and ends Rothco Canvas Parachute Cargo Bag Extra Large Duffle Bag 75L https://a.co/d/03FTtR99
I always used an army duffel bag. Can find them at army Navy stores and they're tough and cheap. And then for the dirty laundry I used a meth type bag. https://www.google.com/search?sca_e...2&dpr=2#vhid=DO0GcWmslXj3SM&vssid=mosaic&ip=1