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It can be held at the correct temperature safely, however it will turn to mush.
Depending on the thickness of the chowder, a possibility might be to make the chowder, strain the vegies, potatoes, seafood, etc. Then you could heat the liquid and hold it hot. When you get an order, add the vegies, potatoes, seafood, etc. back in for each individual order.
However, the best scenario since you are planning on only 30 orders or so, would be to heat to order. the you don't have to worry about hot holding temps, times, and deteriorating quality.