Is there a way to preserve trailing whitespace?

In InDesign 13.0.1 on Mac, I have running headers using text variables that begin and end with an en space. Those that are left-aligned (or left Away from Spine) display both en spaces but right-aligned (or right Away from Spine) headers ignore any trailing whitespace.

This isn't a running header/text variable issue. I realize that any right-aligned text ignores trailing whitespace but I'm providing this situation for context. The attachment illustrates the following:

My running header style has a Paragraph Rule above in one colour plus an elevated Underline using the text colour. The result is a dual-colour rule where one side can automatically adjust as the header length changes section-to-section. I want this expanding line padded on either side, hence the en spaces. Combining styles in this way means only a single style needs changing in any given section rather than 2 separate elements.

I tried setting a Right or Last Line indent but it pushes the elevated Underline away from the edge. Using an inset space on the right moves everything in.

Is there any way to get InDesign to preserve trailing whitespace or do I need to approach this differently? Am I stuck nudging right-hand headers inwards next to a similarly styled box for padding? Or adding some sort of "invisible text" as padding? One is fussy, especially in a long document. The other seems hacky as it adds unnecessary text which could be problematic for accessibility.

Any help is appreciated!