ref: #30139

twinx is very useful, but positioning the active spine requires a fair bit of boilerplate and knowledge if you dont' want it in the default position at $x_{axes} = 1.0$. I think it would be relatively straightforward for something like twinx(spinex=1.2, labelcolor='C1') to be an easy way to specify where the spine is to go and that we should label the color differently than the default.