I've done a couple months in Scotland & NZ, and managed to get all my clothes into my carryon with packing cubes. The clothes I pack can be mixed different ways to get multiple outfits with fewer pieces. I usually have to wear my coat/scarf, and heaviest shoes onto the plane
My go-to travel and hiking pants/shorts are Prana, made from stretch zion
Stretch Zion Fabric for Women's Pants & Shorts | prAna
Even the 'skinny' pants are so stretchy I can boulder scramble or pretzel myself into an airplane seat. The fabric is light and stretchy, and dries incredibly fast. I have a bunch of the skinny leg styles (Meme and Brianna), that can be dressed up a bit for in town.
I second
@outofofficebrb about the wool tops! The super light merino wool stuff is great, and stinkproof
I love Icebreaker, which is painfully expensive, but I look for clearance & at REI Garage sales. For undies, I found any of the light synthetic stuff dries fast, so no cotton. Bras are the biggest pain. If I'm sweating during the day, they need daily wash, but the lining doesn't dry overnite. The quickest drying are the least supportive and may not be lined/padded. I use merino wool bras with cup inserts if I'm going to be sweating and pack at least one 'real' bra for other times.
Dr Bronner's is a great all-purpose soap/laundry wash. I use a big ziplock bag to wash stuff, give it a few shakes, let them soak a few minutes, and rinse! Most toiletries I buy when I get there, so I don't have to haul them & get through TSA
I travel with a ton of medicines, including pain meds, so I'm very cautious about the laws. I have a letter from my doctor approving my rx and the dosage, keep them in pharmacy-labeled bottles, and travel with them in my purse or carryon bag (never checked luggage). The drugstore can give you smaller labeled bottles with your rx on it. I keep all meds together in a clear ziplock, but I've never had customs look or ask me about them. I transfer what I need for the day into a pill box.
In case my passport and driver's license get lost or stolen, I have photocopies of them, and keep them seperate from the originals. I also have pictures of these (and any other imp docs, like med insurance) uploaded to a cloud drive I can access. I depend on Google Gmail & Drive, and have had the overlord burp and randomly lock me out, so I print & carry Google backup codes to get back into my account.
And Global Entry is worth it! There are connections I would have never made, without the fast pass :/
Enjoy!