CLDR ST forum post http://st.unicode.org/cldr-apps/v#forum/fr//27008 brought up that whitespace should be marked up in ST, as already bidi controls are marked up (e.g. <RLM>).
The case in [|/trac/ticket/11173] illustrates how important it is to be able to easily check presence of proper whitespace characters.
In the cited forum thread, Philippe Verdy suggests using colored boxes with identifier inside.
Maybe a color code would allow to unify standard text rendering and space identification, as commonly we need only U+202F with certain punctuations and between numbers and measurement units, and U+00A0 in some other cases such as a number followed by an assocoated word.
Please take this as a feature request.