Back painted (lacquered) glass Radiance material definition

Hi Radiance friends,

What might the simplest way to model back painted glass as a Radiance material? We are producing Radiance renderings focused on the glass reflection of a bright surrounding space and the interior partitions are back painted glass. We need to run a lot of iterations so I was hoping for a definition similar to -glass as a single surface (in computation time).

Second question: if not the same method, what would be the best way to model back painted glass?

Something like this: