Just a thought: Would choose rustic as the style and add only the very minimum glam as an accent -- one item or one small grouping of items that "speak to you" -- make you smile when you look.

You might mention that a quilt can have as many colors in it as the person creating it chooses -- as could matching shams.

Quilts would certainly be "comfortable" in a rustic style home.

Another glam item that could suit a rustic style home is a shadow box (image/object) frame -- a picture frame that is about 2"-3" deep behind the glass with objects in it, usually with a relevant background pic.

https://www.google.com/search?q=shadow+box+picture+frame&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiUrO7y4afdAhUK7lMKHUPtBgIQ_AUICygC&biw=1366&bih=650 

If the home owners have a glam style memento from some trip or time in their life, displaying it in a wood shadow box frame could work well, especially if displayed with a photograph taken by the home owners of a time fondly remembered as a backdrop.

What makes you think "glam"?

Are you interested more in one bold color? or multiple bold colors a few or a lot? a geometric pattern or, for the most colors, a floral?

I like this one:

https://www.houzz.com/products/greenland-katy-collection-quilt-set-full-queen-prvw-vr~59019360

Can you convince them to get another headboard? I'm sorry to say, but that is probably one of the worst door-as-a-headboard interpretations that I have seen.

Just a thought, but are you charging your clients for the advice you are getting for free here?

Glam and rustic don't play well together. And that door headboard is a disaster.

I think what makes rustic and glam pair best is a lighter palette and though rustic, a higher-end quality to the elements. These photos illustrate my point.

That said, I am intrigued by your concept of dark shades and would love to see what you come up with. (And feel free to disregard rude insinuation above about your participation here. You have every right to post AND help someone else design their space.)

Lots of whites with mirrors and wood, some of it distressed with a big glam chandelier or pop of bling comes out amazing. check out mytexashouse.com. maybe this kind of fits the style u are going for. love the pics added by idaclaire.