I've never done a hunting trip from a canoe but I used to guide canoe trips on a local river & lake during grad school -- most fun I've ever had working for somebody else. We typically ran 16' Old Town Discovery canoes for the trips but also had the Guide model -- which had less rocker and a flatter profile. While not as good for faster sections, the Guide model was great for beginners because it was more stable. In each of these, I've managed just fine by myself or with 1-2 other beginners with me + large ice chest. The river I ran was mostly just class 1-2 with a couple of 2+ or 3- sections -- nothing too technical. Lots of weight made things tough, for sure. But it was still doable.
Mad River Canoes were the next best thing and were even preferred by some of the other people I met on the river. The organization I was working for said they would have gone with Mad River instead of Old Town but Mad River only had wicker seats and, for insurance reasons, they had to do plastic-molded seats. So Old Town got the business.
Personally, I wouldn't get too hung up on the length if it's just you in the boat. Even at 235 lb + gear & a deer, you can make it work just fine. Worst-case scenario, you'll have to wade through the shallow parts a bit more if your boat is too small. If you decide to head out for anything much bigger than a deer (say elk, moose, bear, etc.) then the added capacity may benefit you a lot more. But toting 500+ lb of canoe weight will be tough, no matter how long that canoe is.
Of course, if you hunt with a buddy or like to pack a full ice chest, 2-burner camp stove, etc. then go bigger. So much is going to depend on the river you're floating. Slow or fast? Is it a pretty technical river or pretty straight? Do you know the river well -- each of it's turns, bends & hidden obstacles? How is your skill overall? Match the boat with your use and skill as best you can but, in my opinion, there are far more significant variables in-play than an extra foot or two of length.
My wife and I just picked up some tandem kayaks that I'd like to use for hunting one of these days. Kayaks are much more maneuverable, faster and can easily carry all the gear & deer I'll ever get. Plus, they're much easier for a single person to carry. Granted, I can keep my packs fairly light. Any reason why you're looking at a canoe instead of a kayak?