For 3yrs I’ve used a Samsung SSD (1TB) in a cheap Inatek IDE enclosure with UASP/USB 3 connection to an Elgato T2 dock connected to a 2015 MacBook Air by Apple T2 cable. The Elgato also connects to two Firewire 800 drives.
I realized today that it’s worked quite well for quite a while. Now that I’ve written this it will all go to pieces, but until now — good stuff. My 360GB Aperture library lives on that external SSD and I don’t have any real performance issues with it. I use Jettison to undock when I take the Air with me; I disconnect the power cable and the T2 cable.
Which reminds me of some rant I read today about how the Air is the worst machine in existence and everyone should buy a $400 Windows machine instead. I beg to disagree. The current Air is still a great machine. You may not like the non-retina screen (my eyes suck so what would I know?), but you can buy a nice external display.
The absolute best thing machine Apple could do would be to continue to sell the 2018 13” Air but swap the T2 for T3* and make the display Retina. Leave every other thing about it pretty much the same and sell it for the current price.
*Update: Actually, I’m not sure T3 is so great. Maybe just do the Retina and call it a win.