Thanks for all the great replies. Here are some more details:
1. This is/was a proof of concept. I'm not kidding myself thinking I am going to do loaded touring. I posted it in the Bicycle Mechanics section for that reason.
2. There are plenty of practical uses for something like this. I think ultimately it will hold my work clothes in a set of panniers. Others might want to use something like this for a light setup.
3. Like I stated earlier, I loaded it up with about 10 lbs. and went for a 5 mile ride. The bike handled fine. It turned a bit slower, but it wasn't overly dangerous in any way. I rode up to about 35mph. Like another poster said, it is probably not a good idea to go no hands, which I didn't.
4. The rack is a lot stiffer than most people think. That "plumbers' strapping" stuff is pretty strong in this application. I'm not sitting on the rack, so it should be fine with up to 50lbs, although I personally won't put anything heavier than 10lbs as stated above.
5. The strapping has holes in it. It is not going to noise dive(?). I don't understand how it could do something like that, nor do I understand the comment about the bolts and brazeons. Tubus even sells adapters for their racks that do the exact same thing (the Tubus QR adapter).
6. Regarding HillRider's comment, I think I will trim the strapping down when I'm 100% sure that's the right length I want to use. Thanks for the feedback.
7. Yes I do ride with a Superflash in front and back! I ride by a few schools in the morning where parents are weaving in and out to drop off their kids. Being outright annoying is probably the only thing keeping them from plowing into me.
I do not do #7 any longer.