Hello,
Love the game and this forum! (until now I only read, first active post)
Found a recent link to this topic, and gived it a try myself.
Really liked @VulcanFox his test.
I think if you keep a sill on the outside and no windowprofile on top of it, it gives a somewhat more spacious feeling.
Than you can see the inside flooring trough the glas.
Mayby possible with shadows, but not that easy to make it work in the game, i think.
Or the possibility to chose the coulour yourself?