I am looking to do something similar, but trying to find a shower faucet with a lever diverter, like a bath/shower, but without the bath spout.
I built a custom shower for inlaws a few yrs ago amd redesigned the tub spout to connect a hand held shower. The shower setting then plumbed around the back of shower up to a middle rainfall showerhead.
I like the idea of a separate shower control so we don't have to reach out of shower curtain to sink to adjust temp and turn on/off.
Having difficulty finding shower control with hot/cold/on-off that keeps hot-cold ratio as we turn it on-off (instead of using oxygenic's slippery twist valve). Any help finding would be appreciated.
I do really like your mod. Looks great!
Edit: I gotta add, this was a GREAT writeup with lots of details. I may just steal it ;)