Again, I don't claim to be an expert in Ringen but I have studied it a small bit and know that there are a few that do rely on clothing grabs. Petter, for instance, clearly shows Tomoe Nage and multiple other clothing grabs including belt and seat of the pants.
I'm no Ringen "expert" either but you should be able to do Ringen equally well against someone in armor, clothes, or none of the above. If you are relying on clothing, unless the plate specifically mentions it, you are not getting the point. If you want to use Western gees for aesthetic reasons that's fine but realize it is purely for prettyness.