Do you want to kill more deer or do you want to muzzleloader hunt for the challenge of it? You can buy muzzleloading rifles that will shoot into a minute at 600+ yards if that's what you want to do, range the deer, dial the scope, and let fly. From my personal knowledge it's not much if any harder than the same shot with a 308 and a mediocre bullet, but to be clear I don't have a ton of experience with them. Lot's of the common 209 primer inline types are good for 200 yards pretty easily.
Lots of experience here with truly LONG range smokeless muzzleloaders as well as inline types and traditional types whether cap guns or flint. What you want to do will help others relate their experiences.
For me, I want the challenge of hunting with a primitive weapon so I hunt with a traditional style flintlock. Real black powder, patched round ball, iron sights, state of the art 300+ years ago LOL. It will shoot sub 3" at 100 with a capable operator. Kills at 100 also, and that's getting solidly into 'long range' for the equipment in my book. My flintlock is very comparable to bowhunting, just adds 50 yards or so to my range. I primarily bowhunt and muzzleloader hunt these days as it is way more satisfying to me personally, but I also love long range shooting and that's why I hang around here.