Reflectix behind dark tinted windows?

I am using corrugated plastic to make privacy covers for my transit connect. I have the passenger version with dark tinted windows.

Would it be beneficial to use reflectix on the corrugated? Would it make that much of a difference behind the tinted windows?

I will be covering one side of the corrugated with black felt for use later on in the colder months. What are your thoughts?

Thanks