I think if I were in your place then I'd be looking at the Marlin 1895SBL in .45-70 Govt. Short, light, reliable, durable and powerful enough to make any bear in the woods have a very bad (and short) day. Comes in stainless so it'll resist the elements well, and the laminate stock will be stable, strong and weather resistant, not to mention attractive.
It come with built in ghost ring sights and a picatinny rail for easy scope mounting. Put on a 2.5-7x scope on it in Warne QR rings if you want a scope with the option of using the iron sights, and you'd be all set for what you want to do.
Mike