That's a pretty good idea, Michael.

I think there maybe something else you could try too:

I don't use the 'dashed' hidden lines, I've told the .ini to make them solid, so I have a cleaner image. The dashes are distracting to me.

Instead of red or some color like that, you could follow suit the way you've done with the other different types of selections.
Either with color or transparency level.

Let's say; your selected object could have hidden lines that are 50% transparent, and all non-selected objects could be set to show a slightly visible 20%.

Or, the selected hidden lines could have a special hidden-line-selected color that would inherently work with the chosen color scheme for selected objects.

Just some additional ideas.