There are many sources for external cases or cables that directly connect to SSD mechanisms and provide you with USB3 connectivity to your computer. These are fairly light and easy to carry with only only cable. I have been using these for several years - even include a volume that has full duplicate of internal SSD (just in case something really bad happens to the internal one, you can reformat it and copy the contents back from external to internal, if it is not completely fried).

For reasons that the "Air" model was or may not be readily upgradable, I have stayed away from it from the beginning and have used MBPro(s). The recent versions of 13(something)" is light enough to travel with, has decent enough performance (minus the dedicated video processor like its bigger sibling).

I'm with you on shooting with the largest image size setting your camera permits. I save photos in camera's native RAW version + largest & least compressed jpeg.