I ordered the brackets that
@83oldyoda4x4 posted, when they come in I'm going to figure out which amazon turnbuckles I need and go that route. I can draw up some over the top sheet metal bracket for this, but I think that would be making things a lot more complicated than needed. In my case I don't really see the need for a quick release since you can open the lid. I might throw some kind of pin through the lid incase the latches on the cooler were to come loose during a flop or roll. I learned my lesson on that a long time ago, I don't like having to clean up a bunch of stuff off the trail after a roll.
@Jody Treadway Let me know of you still want some kind of sheet metal bracket and I'll see what I can do. I'll post the turnbuckles when I get that figured out.