This is my third endless summer trip and I am starting to refine the gear I am carting around. I can almost carry everything at once but normally I don’t have too, The backpack in which I carry two computers, (why two computers? why not) is fine for travelling on an airline, where one of the camera also goes in the backpack and the second camera (normally the Pentax) becomes my hand carried ba). The art gear travels in my luggage for flights.
In the field I leave the computer back in the room (or car) and just carry one of the cameras and the sketching gear, with papers (A4 or quarter watercolour sheet size) already taped to my A4 plus sized drawing board that fits inside the little red backpack.
For more established and longer sketching I have an A3 sized sketch board in the blue folio which takes half sized Watercolour paper, it also has a bolt on the underside that can screw into a tripod for a make shift portable easel. The blue folder also holds about half a dozen watercolor sheets and a couple of extra sketch book.