Can you open the trunk with the Saris Bones 2 trunk rack attached?
I have a different Saris rack that has one top foot and two lower feet like the one you show, but I didn't find it on their website now.  It has six straps, two top, two side, and two bottom.  I use it on the hatch of a Lexus CT200h, same as Prius C.  The lower feet sit on the bumper for me, not on the hatch.  I can open the hatch when no bikes are installed with no problem.  In fact, I open the hatch to install the rack because the side and bottom clips are hard to get on with the hatch closed.  I had a previous Thule rack with the same experience except that you have to keep your head out of the way when closing the hatch.  All the feet of that one sat on the hatch.