How do I Hang a 2 1/2" blind(s) on the styrofoam walls?

Randy
Mounting anything on thin filled RV walls can only be described as a major challenge. I found these hollow wall screws searching for an anchor for my problem. Purchased longer than needed and found you cannot use them as they strike the rear wall before they are far enough in to compress. Trial mounted one on a thin wood shim and went back and got a shorter length. They are clearly the product of choice for RV use and stronger than I expected. Glad it solved your problem too.
Bob