After screwing around with the hood and taking out all possible slack in the hinges, I was left with the much reported issue of "OK without struts vs Not OK with struts connected."
Attached is my solution (simplest I came up with) to stiffening up the location of the strut supports on the hood (on those very very flexible flanges of the liner). Bingo!
Does require the sides of the duct to be notched (I'll replace the bulb seal on either side of the notch as I move on)