This will not help if you are not allowed to use lead, but here is what works well for me. I use an auto-loader, IC choke, 1.25 oz of lead 5s over a decent charge of Longshot for about 1400 fps. I only hunt private ground and hunt behind a GSP, so my first shot is usually close, but I have plenty for a second shot (once in a while a 3rd) if required. I am not an exceptional shot, thus the IC choke (and my normal target range), and I use only one gun and the same shells all season, I am pretty capable with my set-up. I migrated to 5 shot around a decade ago from 6 shot, the primary reason is that less shot remains in the meat.
I would make sure you have IC and modified chokes with you, so if the normal shooting seems close or further-out, you can change and increase your chances on connecting. Get out with a few different types of shells you are considering and shoot some paper from 25-35 yards with a few of each to just make sure they pattern decent....and you will know if your pattern is going where you think it should be. Good luck and post some pics from the hunt.