Dig it. I love etrack, I used to drive cargo and worked on alot of loading docks. It just makes things so easy. You should conside making a pair of load bars for it. Makes it easy to move large objects with a single cinch strap.
Here's more pics. I fabricated the adapters from 1x2 tube and some plate, it's bolted to the stock holes in the boxside with m8x1.25 and m6x1.0 bolts. The E-track bolts in place with short m6x1.0 button head allen screws.
You should make more of these and sell them! Great job! I did something similar with L Track on my old 2004 Nissan Frontier and it was so handy, got so many comments when strapping things down. L Track post