Livre d'Or

I want to make it clear to my friend that I'm not judging her for generally wearing more revealing clothing than I do.

is that the message conveyed, though? (Possibly, if you have discussed it) Absent conversation explaining that I would assume that someone who normally dressed very modestly and changed their style somewhat around me either

1. Felt safe from judgement around me and had relinquished some sort of modesty-policing in my presence (which would confirm my objection to modesty rules)
2. Was erroneously trying to imitate me or some standard of cool associated with me
and/or
3. had simply worn that outfit for whatever reason, and i'd pay no further attention.

Surely the *good* option here is your friend doesn't actually notice at all? If your friend not only objects to modesty rules *but also to people dressing comfortably and habitually in ways that read as modest*, I'm not sure that you wearing more-revealing clothes is going to *help* that situation at all.