Does the TENS unit work well for your back pain? I would need something like that for my neck shoulder. That's where I get most of my discomfort while sewing for more than an hour.
I recently treated myself to a better chair with a good lumbar support and my sewing area is set up in almost a square so all I have to do is "wheel" myself around to whatever I need (sewing machine on one side - next ironing table - behind serger - other side work table). I have just enough space to walk out of that work area but it works for me. My cutting table (with my bar stool) and fabric are in the other bedroom. The bar stool has really helped to relieve my back pain when I have a lot to cut. I cut the long cuts standing up, then do the sub-cuts sitting down.....HUGE difference in how my back feels.