I basically just screwed the amp in at the top with a screw on each side. The screws only went into the plastic panel and not into the support. and if I need to take the sunscreen panel off it works the same you just have to lay it down and be easy with it since the amp is still installed.

My only problem is that my rubber bushings on the clamps that hold the panel on are getting worn out and the amp is putting extra weight on the panel so it makes it sag but im going to try and use some of the velcro strips with adhesive on both sides across the very top of the panel near the window to give it some extra support.

 

I haven't put my amp on the cargo cover yet and I'm having the same problem as you.

Mine simply falls off when I hit any big bump or pothole. I tried double stick tape and the velcro, but my clamps are complete shot and broken along with the mounts and rubber bushings behind them.

None the less your amp mount looks sweet in that spot, but I fear if I do it with a Rockford Fosgate R500-1 it will just do more damage and completely rip out the clamps and bushings.

If you come up with a good solution to secure that cargo cover please let me know! I'm attempting to secure mine this weekend.

 

The previous owner of my Jimmy used some rubber compound type stuff. Almost like the same stuff that holds the plastic behind your door panels. Its works good, hasn't fallen off yet although I DO NOT have my amp mounted there.

Hopes this helps!