I'm sighting in a Remington 11-87 Slug Gun for my cousin 20GA and we hunt in a area where you only get 20-70 yard shots maybe a freak 100 yard shot every blue moon.

I was wondering If I should sight in at 50 or 70 and if 50 should I hit bullseye or be high and if so how much?

I want to be able to be dead on at 20 or 30 but still reach out at 70 or 100 if I have to whats the best advice thanks.