As soon as you mentioned it was on 321, going around to catch 321 was my first thought. Time wise, it will probably be about the same, just more miles to avoid the traffic which could be horrendous.
If you get off at exit 435 on Hwy 32, there is a Super Walmart which is a good place to top off on food and fuel. The fuel/gas prices there are usually the cheapest in the area. Your other good choice for food and fuel will be the Food City near the campground.
While in the area, make sure you check out Hungary Bear BBQ and Applewood Farmhouse Resturaunt.