I think the attachment rings look good! With a plastic or aluminum gunwale, I'd drill, but I agree with your decision to not drill through the unreinforced part of the royalex, or all the way through the wood.
One thing I can't tell from the photos, are the end bags tied off somewhere under the bow plate? If you can get a "leash" on that pointed end grommet, that will help keep them from "squirting out". Air bags in general will try to work their way around the tie-down ropes, especially with the forces of current pushing on it and maybe even sloshing it back and forth. Many folks outfitting boats for Class III and above use more ropes, and even nets across their bags, for this reason.
Also, are you planning to add thigh straps and kneeling pads? If this boat will be used for milder WW where these are not needed, then I think you can get by with just the end bags much of the time. I once experimented with a boat by sinking it at Rockport, below the main feature, and just dragging it to shore in the Class I minus current there.
Trial 1 - no air bags - it was difficult to get the boat quickly to shore, and it took a small beating just bouncing over a shoal with no major rocks and really nothing it could get pinned on. (This was particularly problematic because it was my wife's boat, not mine, that I was experimenting with...)
Trial 2 - very small end bags, no center bag - I was able to swim the boat to shore easily.
I think you'll be pleasantly surprised with how much just the end bags help even when you leave the center bag out - that may cover a good % of the times you want to use the boat.
I recommend you do a similar experiment at Rockport or some nearby lake soon - swamp the boat, move it back and forth, and see if the bags stay in place and do what you want them to do. You'll either see that it is doing exactly what you want, or, know if more tie-downs are needed and if so where.
`Believe me, my young friend, there is NOTHING--absolute nothing--half so much worth doing as simply messing about in boats. Simply messing,' he went on dreamily: `messing--about--in--boats; messing----'
Hopefully the pics are clear, but here's what I did. Ran paracord through the eyes for lacing in the center. I didn't want to glue D rings there because I'll occassionally need to move the center bag back in order to solo from the floor. I configured it so I can just move the bag back against the seat and tie the corners down against it. I'm hopeful that running the paracord through all the corner grommets will be sufficient, but I'd love to know what you guys think. I did glue down D rings on each end. This is my first outfitting job, so please feel free to critique as you see necessary.
