The fit is pretty roomy inside indeed, with seats folded you can put a mountain bike in there with the front wheel off no prob. I would not be enthused about taking one up to the mountain to go ski/board though. Unless you live in the snow and can run dedicated snow tires for winter it means you're going to have to deal with chains. And even occasionally that's a real PITA.
This being the forum it is someone will be along shortly to say that I'm wrong, the fit is a great adventuremobile and they tow their boat with it, ran the rubicon with minor mods and so on. I can just say being from a mountain town and now living in semi-rural and driving to the mountains 3x times a week for biking, hiking, boarding, etc. that you'd be way better off trading that fit for a subie.