I did a second one. This time I was more confident, so took some photos.
Here are all the bits I used. The CBI Astute and ESP-12S up front. Isopropyl alcohol and cotton pads for cleaning. The trusty old Weller, solder and flux pen. A rusty old bench vice that is normally used for welding and...
First ... HUGE thanks to @gbyleveldt for the excellent guide on Tasmotizing the CBI Astute in the original post.
I've managed to get this done, even though I don't have much in the way of specialized equipment and definitely do not sport ninja soldering skills. I thought I'd share a few notes...