I have only been looking at getting a c50 or for a friend to get a c50, but have used n.v. scopes before. At that range I would think action will be fast and hoping you have some shooting sticks or something similar to swagger clip on swivel sticks so you can have the shotgun up and maneuverable if some thing shows up and with the thermal hope you can catch them early then lip squeak them in to 30 or 40 yards
I dont think you will need an aftermarket light to illuminate more, 75 yards can be done with most factory supplied i.r. have you sat out yet with it and can you see the other side of the openings?