I am glad you worked through your dilemma, and you did work for it, your setup is good, I do like the surefire better, but if it didn't fit and you got no relief from the factory, then by all means press on, and give it back.
Your now updated personal set up is great, don't do the ghost ring route, been there done that, your current setup is good to 50 yards quick, a ghost ring can be more accurate, but slower, and I mean much slower, with a light and in the house to the front or back yard, ( for most of us ), your shotgun has got it dicked, period.
If you like I have a MMC ghost ring setup, but for remington, that I would give a forum member a great deal on, good stuff, but after a lot of shooting, not what is needed, now if I lived in a state that I could not hunt deer with a rifle, then I would dedicate this sight to a good slug shooting shotgun and have no remorse.
PS, how is the spider bite??? Best of luck with the healing.