I think your choke choice is perfect and your rational sound. Better to set it up to encourage maximum usage than optimal use for something which will rarely be done. It would be a shame to build it and almost never use it because it too tightly choke to shoot skeet with or even a few sporting clays. And clay targets are year around anytime type of game.
I think you will find those chokes are more versatile than you think. I have found that by altering shot size and velocity that you can get a lot patterns to go from more open to tighter giving you the same effect of changing chokes. You can not go from IC to Extra Full but you can go from IC to IM and IM will give you all the range you need if you do your part.
I shot some very interesting patterns in both 28 and .410 with larger shot seeming to pattern much tighter than the number would call for. One 28 reload I used was very effective at late season pass shooting late season doves and this year a .410 reload was my go to choice for early birds. The powder was 300-MP and with it I got a 1250fps/6000psi half ounce load that was real soft shooting load that still killed dove out to 25 yards. Bump it up to 1300 fps, half ounce loads at 6800psi to use when the birds got wise or for sporting clays. And that was a measured 25 yard shooting limit, not where the birds fell. I always like to set a real limit when I shoot a .410 because I need to know my limitations and always when shooting a .410.
