Have you considered flying to Chiang Mai? It can save 12 - 18 hours in travel time. Note that it looks like we're in for a potentially bad bout of flooding, with heavy rains in the north, and dams having to release large volumes of water flooding many areas that the Chiang Mai train has to traverse. Obviously, this sort of thing could impact train travel in November.
Have you already purchased the train ticket? Some trains and classes of service can be sold out.
The train from Bangkok does depart from Hua Lumphong, but it does travel north through the city, and you can catch the train at some stations on that route.
I guess the options are to stay near the airport, then head into the city (via the rail link, changing to the subway at Petchaburi - the subway currently terminates at Hua Lumphong), or to head into the city and then get to the train station.
There are some hotels near the train station, and the neighborhood is pretty interesting and as safe as anywhere; and you're a short walk to Wat Traimit, Chinatown and a few other sites.
Do you have a lot of baggage? There is a left baggage at Hua Lumphong, not sure how "secure" it is? There are lock-box facilities showing up as well.
https://www.lockbox-th.com/location