What are you wanting to do with your window treatment ?
Protection from sun/glare ?
Purely decorative ?
What material are your windows? Aluminum ? Wood ?
Are you sure something couldn't be attached just to the outside of your glass on the outside of the trim ? It could be tricky because you have those window cranks right there. Any blind you have even if you mount it to outside trim (which is fine to do ) will have to stop before the cranks- looks like. I'd measure to bottom of trim , but stop them short of the cranks, otherwise they will stick out over them & not look right. If you hane normal bottom up blinds- they can still be the silouette type, thet would look fine mounted to the outside frame & then put a decorative valance over the top. I'lll try to find some pics- then figure out how to post them.