I have 1/2" pvc frames and then Boscoyo Chromatrim zip tied to it. I have just two hooks at the top of each window that the frame hangs on. If you can't or don't want to drill you could put some kind of bolts and nuts thru the pvc that would put pressure on the window opening that could be used to keep in place. i have heard of some fols using the expandable curtain rods that have springs inside them to cause a pressure fitting. I have two windows that are flush with the siding and two windows that are recessed into a brick wall so slightly different but similar mounting. My frames are all interchangeable and can be hung in any window because I made the all the hooks and hole in the PVC using a jig so that they all line up correctly.
