Cool project AC!
I have to admit, it took me a minute to grasp your concept.
When I read the title of the post, my mind's eye had you adding a rocket launcher to your hardtop!
Instead, you have used your existing rocket launchers to extend a roof over a portion of your rear deck.
I understand the use of PVC rather than aluminum due to weight but I'm wondering how well the extended roof will stay in the rocket launchers during a rough ride.
Let us know once you get a few "field tests" under your belt!
Pretty inventive idea and I hope it works for you!