I wouldn't recommend hooking a grab hook onto the stake pocket. I prefer not to hook a grab hook to anything but chain. They always seem to jam up on anything else they are hooked to. Also, the pressure of the chain being snugged down with only the small contact point inside the hook will likely bend the edge of the stake pocket. My preferred method is to loop the chain through the pocket and hook it back to itself, although D-rings would be handy if my trailer had them.
On a side note, I also had a recent trailer epiphany. A month or so ago I bought an ex-rental trailer for tractor hauling, lumber, etc. Never particularly liked the surge brakes, but I figured I could live with them because of the good price on the trailer. I always felt like I was using the truck brakes too hard and had too little safety margin in an emergency stop. While hauling about 3000 pound of lumber, I had to try a quick stop on the interstate due to traffic backed up behind a fender bender. I had kept a reasonable distance back from the car ahead of me, but when traffic stopped, there just wasn't enough room. I was lucky enough to find a gap in traffic in an adjacent lane that I could duck into, so no damage done except to my shorts. Wasn't near as exciting as Dargo's ride, but it was still enough to send me out trailer shopping again. As much as I hate to spend the money, I'll trade in this trailer and spend whatever it takes to get what I should have bought the first time.
Snug her down good and drive safe...