Playing Technique with Repeating Symbol Line & Glyph

I’ve created a couple Playing Techniques for fast and slow jazz shakes that I’m using in Expression Maps to trigger different samples. I’m trying to figure out a way to display them. If I only used a line, that wouldn’t work, because it wouldn’t trigger the expression map change. The goal is this:

This is accomplished by setting an empty glyph or no text and using the line as an extension. However, when it’s first entered, it looks like this:

You can easily lose it if you don’t immediately lengthen it. It can be selected in Engrave mode if you click in the right spot. So I added a glyph. That solves one problem:

But creates a new one:

Even though the glyph is the same symbol as the ones the line consists of, it doesn’t repeat seamlessly when extended. I’d rather not have the text “shake” at the beginning of every shake line – I don’t think that’s necessary.

Changing the X offset of the glyph has no effect.

In Engraving Options > Playing Techniques > Continuation, I changed “Gap between glyph playing technique and continuation line” to -7/32 spaces, and that seems to work great in this situation, but what if I want a Playing Technique with a glyph line extension that’s not so close? I couldn’t seem to find any settings (in playing techniques, line builder, line body builder, or otherwise) that affects the horizontal spacing of elements in individual Playing Techniques.

I also tried creating my own repeatable symbol with an X offset and putting that user comp in the Playing Technique as a glyph, but it looks the same as when I just used the built-in glyph.

Is there a better way to do this?