Thanks guys, I ended up going a slightly different route. I realized there were some very specific places I needed tie-down points and more OEM tie-down loops were exactly what I needed while still looking like it came from the dealer that way. The 4Runner loops have friction in them and don't flop around and make noise like many of the other cargo loops I've seen, so I bought eight more (!!) and started installing them where they were needed.
One added on each wheel well:
(There were already loops in each corner from the factory):
I have some more going in on the floor of the backseat area. My wife and I now have a 2-month old baby and now the entire backseat needs to be useable for the car seat and for my wife to ride back there with the baby on long trips. If something went down on the highway I wouldn't want unrestrained cargo to take a life, so I'm currently adding more in the floor of the backseat area to restrain a few more things. For example, our daughter won't need the footwell below her carseat for several years, so that makes a good place to tie down our 5 gallon water jug. Basically, I need more space than ever before and need our stuff secure. People are too busy texting these days to do any decent driving, so it's better to be prepared for the worst.