I struck a happy compromise, finishing the gusset and moving the stitches to the waste yarn out of my house but at my knitting group. I took another project with lots of mindless garter stitch to my long committee meetings. It’s best to know your limitations, right?
I’m still proud of myself for doing both the right and left thumb gussets simultaneously. It took a little marking up of the pattern, and a little concentration, but all-in-all not too taxing. This might bolster my confidence enough to attempt turning two simultaneous sock heels one of these days. Who knows what hilarity will ensue if I try that!