Leupold 6x42 should work fine. Long range will be dependent on your rifle and skills, but if you can't see it with that Leupold because it's dark then it's past legal hunting hours for deer.
I don't own any gamer guns, and I don't hunt any Ag fields or power cuts, so past 350 yds just isn't going to be needed with my deer rifles. In my situation, I have no use or need for spinning the dials in the field. OTOH, 250 yards and back into the woodline with 5 - 10 minutes of legal light is a very common shot, and I find the Leupold 6x42 plenty bright.
