I haven't ridden through Camden, but I have ridden through other cities, and the middle of the night is a pretty good time to do that. There isn't much traffic, and the people out on the streets are generally going about their business. Granted, it's not always legitimate business, but it's not my business and I haven't had any trouble.
While its violent crime rate had dropped recently, Camden is still one of the most dangerous cities in America. IIRC, the murder rate is again rising. Best way though the city are the major arteries. Try to avoid small/isolated streets/enclaves.