I am in somewhat similar situations; I fly for weeks at a time, often changing climates several times during a trip. I can't follow the FT mantra of 'carry on only', which tends to be the Monday out/Friday back type of flyer. I'm in locations and situations which may range from smart business casual (not the American version), to formal business attire. I may be in the jungle one week and in a formal office in London the next.

I carry enough in my 20 inch Travelite Delite and Longchamp flight bag to make it through a week or more if required with no checked bag. That means a full change of clothing, extra tops/underwear/bras, essential makeup and toiletries, tights, 2 laptops, and other essentials. In your case it would mean adding the flight bag but subtracting some of the clothing I carry, so doable.

Worst case I know how to supplement by online purchases if absolutely necessary. Shopping local for clothing/shoes just isn't an option for the very tall, large footed woman in parts of Asia, for instance.