My only experience is with the “Auto Train”, a long distance nonstop Amtrak route between northern Virginia (near DC) and central FL (near Orlando) where you can load your vehicles and bring them too. Kosher food was available for dinner in both the sleeper passengers’ dining car and the coach passengers’ dining car. The meals were frozen double-wrapped chicken and rice airline style meals heated in an oven before serving. Breakfast was also served in the dining cars the next morning, and consisted of Kellogs cereals (served with non-CY milk), fresh whole fruit, and orange juice. There were muffins that were not kosher, and the servers (seeing that we were frum) offered us heated bagels that came from a package bearing an OU, but since they were not in a sealed container (nor double wrapped when heated), we politely declined them. I would certainly recommend packing extra snacks, or even your own meal if you dislike plastic wrapped frozen dinners.
Make sure to let Amtrak know that you need kosher meals for your trip, so they can have them ready for you.
BTW – the train cars I traveled in had outlets, but not sure if they had enough juice to operate a kettle. I’d doubt that would even be allowed. It might be better to bring a small cooler with sandwiches.