Sorry Paul, hijacked your post. The front bags on my picture have some LL Bean and E Allen puddle duck decoys in them and they sit very still though they are a snug fit in there with 2 bags side by side. I fit a dozen on the bow, in 2 6 slot bags. I fit 2 dozen on the back deck in 2 12 slot bags. I keep the center of the rear deck open to reach the shifter and motor easily. In the cockpit I usually have 2 or 3 more 6 slot bags. I leave the deck area under the dodger for my coat, blind bag, heater, etc. All together I can transport 4 1/2 dozen decoys in my sneakbox. Typically when I have that many, at least half of them are long-lined, it is too much work to individually line that many decoys unless I am hunting an area I can walk them around in which is not always the case or the tide.
The concern with higher decoy boards, or any is access back into the boat. How well can you climb over them. Mine are as high as I dare. If I was to go higher, I would also go more robust to handle the stress of getting over them. Mine are easy on and off. The rear boards are 3 pieces, held to the box by shockcord at the oarlocks, and limited in the rear by design, and the front are held in 4 locations by captive hardware, though I don't take them off. Even in the summer I leave them on as they do a nice job of preventing anything falling off the box.