You can add hulls to any brew though there not needed. There is no set ratio on adding them, I have used 1 # on a 10-14 # grain bill. However I have quit using them all together.
The grain bed depth is my real concern with my low grain bill v mash cooler size . I would have thought that if I add more than an an optimal amount of hulls I could end up creating a worse drainage problem than that that might result without them.
With the present grain bill and doing my calculations of water uptake I reckon I end up with a tad less than a 4" mash using a water/grain ratio of 3.25:1 In that event the 12" bazooka would only covered by approx a 3" mash. I will give your 1 lb recommendation a try.