As I stated earlier - many thanks to all who helped me see the error of my ways. Below is a recap of what I learned and my install.
1. Don't use toggle bolts. You'll need to make a very large hole in the side panel and the backside of those panels have a variety of things behind them - from metal frame to ridges of plastic to fasteners, etc. Thankfully other uses guided me away from toggle bolts.
2. Do buy a trim removal tool kit - It's very good use of $10.
3. What's behind panels and their backside structure varies from one side of the vehicle to the other. Pull both before you determine where you want your holes so you can have even/symmetrical placement.
So - here's what I ended up with - and am very happy:
I utilized this trim kit:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I utilized these tie downs - The D-ring area is about an inch, they are solid, and importantly - the D-Ring doesn't rattle.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
While the kit comes with screws, I wanted something a bit longer since I needed a fender washer, and a lock washer, in addition to the nut. I picked up some 1/4" diameter machine screws in both 1" and .75" lengths. I ended up using the 1" length due to the structure on the back side of the panel - you'll see that below in one of the pics.
This was my first time taking off panels but it's pretty simple. Insert tool, make a gap, and wiggle your tool until you hear a clip pop open. I should state, I didn't TECHNICALLY take off any panels, i just unfastened enough clips and screws to get the access I needed. I unscrewed the screw inside of the cargo cover indentation. Just pop off the cover and it's a phillips. I unfastened the 3-4 clips on the top of the panel and then I removed the plastic "T" tie down right near the tailgate. Just a quarter turn and it pops out. Again, there is a phillips screw underneath.
Once I had the top of the panel loose I pulled it back to see what was behind it (a small Maglite comes in handy here). I had three considerations for where to place the tie downs/drill the hole:
1. Where would the tie down be convenient. For me, I wanted it somewhat it in the middle of the cargo area (front to back), and ideally wanted something to be able to sit in the wheel well tray and also be tied down.
2. What is behind the panel in that location. The fender washer I chose was big to maximize surface area and thus strength of the tie down. This, however, makes install in a couple spots tricky given where metal or clips are located.
3. I wanted to leverage the structure on the back of the panel for strength -- although I didn't originally anticipate this being a need. You'll see from the pics I chose a spot where the fender washer would spread over three "ridges" (left, right, and bottom).
Once i picked a spot, the question was how to replicate the location on both sides so it was symmetrical. I knew I wanted to use masking tape over the drilling area so I didn't damage the finish of the panel, so I just used a couple pieces as my measuring guide. The vertical piece of tape in the pic is aligned with the ridge on the back of the panel. I then placed the fender washer over the tape so one side hit the edge of the masking tape (and the ridge), and the bottom edge of the tape (and the bottom ridge). This ensured I hit all three ridges and had maximum support. I did use a measuring tape just to validate.
Note: Drilling into a panel for the first time will raise your heart rate and make you sweat!
Once I had the hole drilled I added the washer, the lock washer and the nut. On the side with the jack, the panel comes out further and you can easily use your fingers to tighten. On the side with the cubbie, I had to use a needle nose pliers to hold the nut. Be careful not to drop the needle nose or you'll be taking out a LOT more clips to go find it.
With the nut tightened and being satisfied with everything I reassembled. I started with the two screws on either end and worked my way to the middle. The clips pop back in easily.
I hope this write up helps you with your mods. Feel free to reach out with questions.