When I'm hitting bumps and/or pot holes on the road, there's an extremely annoying clankety knocking sound, which sounds like it's coming from the back area of the hatch/trunk. It almost sounds like someone is trying to open a locked door and is wiggling the door **** but can't get it open. It also makes a low pitched squeak at the same time, but the knocking sound is much louder.

I have a 99 spec wing in the back, so I took it off and put double sided foam support tape on it thinking it might be the wing that's loose, but turns out it wasn't. I also did the same for the snap-plastics in the hatch thinking it might be hitting the body, but still that did nothing too.

Any ideas? Am I needing to replace hatch parts?

 

2 things come to mind.
1) your diff mounts are blown.
2) Your spare tire isn't secured right. This happened in my DD. The tech that fixed my flat put the spare back in the trunk all wonky so that when I hit a bump I'd hear a bump and a squeak from the rubber rubbing. Mounted the spare correctly and no more squeak.

 

Your problem is as old as time, well, as old as our 7s are anyway. In the search drop down enter: toe link clunk
You will get approximately 190 Threads with thousands of posts on the subject. Start with checking out the rear suspension very carefully. If you've got lots of mileage the toe links will probably need replacing, along with anything else that is busted or loose in there.

 

You might want to just see if the hatch latch needs adjusting.
Hatch Rattle Fix

 

also search "pillow ball bushings"

 

Lots of good suggestions so far. One more would be to make sure that your jack assembly is snugly fastened in place. Mine wasn't, and made a similar noise many years ago.

 

THIS^ is what fixed it! I overlooked something that was so simple, lol. Thanks for the input guys.

 

glad you found it. for me, it turned out to be that my aftermarket shocks, left rear top nut had worked loose.