Rather than a backpack these days I'm trying to optimize for the most useful stuff, and clothing that can fit in an item of luggage that will weigh 48.8 lbs on

Rather than a backpack these days I'm trying to optimize for the most useful stuff, and clothing that can fit in an item of luggage that will weigh 48.8 lbs on a hanging scale, so I can check it in with most airlines without absurd fees. For business trips, the longest possible length of time I can go without needing to do laundry mid trip is a time saver.