I don't ever remember the private railroads cutting cars on Florida bound trains in the winter months even after the holidays. In fact, they would add cars. I lived across the highway from where the Southwind ran in Sellersburg, Indiana in late 1965 and 1966 when the trains was very well patronized. I used to track the number of cars when I would see it go through. In the winter months, it usually had a full capacity of 18 cars. Often times, in winter there were cars borrowed from other railroads. The Northern Pacific Lounge in the Sky Dome Sleeping car was standard from mid December until the end of April. In the off season summer months from May through September the Southwind usually had 11 revenue cars. I also know the New York-Florida trains added lots of cars in the winter months, but unfortunately, that market has somewhat evaporated under Amtrak.