I'd be willing to bet that 95% of the places you will be going in a 4WD could be safely navigated in a 2WD, especially if you bring along chains. The only thing I would be worried about in a sedan is ground clearance--in my truck I think I have about 3X what the GF's car has, for example.

If you are worried about getting stuck, make sure you pack a fullsize shovel (two are better), the aforementioned chains, a highlift jack, and a come-along. Better yet woiuld be a winch--a nice $300 investment. When you have all of the above and still can't get unstuck, then maybe that would be the time to hoof it.