Fact: A hunting rifle without a sling simply denotes lack of experience. The list of reasons goes well over a dozen.
We're back to "hitting a man size target" at range. So an AK remains in the running (if your missing a man at 300 yards don't blame the rifle!), though an SKS, and even M44 Mosin Nagant would do fine. But being a "truck gun", the ones I've seen didn't get much love between shootings. Better to go with something in Stainless.
I'd sacrifice the shooting at 200 yards idea to have a Mossberg Mariner in there myself. ULTIMATE versatility out to about 100 yards. If your shooting further than that, it's probably going to be a little more planned out, and you should bring along the appropriate tool for that trip.
Just my opinion.