How much total weight would be safe back there i wonder? No instructions came with mt rack, so no clues there. I would definitly get some of those clamps rather than drill through the roll hoops.
There's some room in the boot, a couple of soft bags would fit nicely. Passenger footwell. I wouldn't put more than 30 lbs on the rack. As for drilling two little holes in the roll hoops, no problem. My head is a good 4 inches over the roll hoops so they're more decorative anyway ...