If you're getting off the westbound train, you'll have several options willing to pick you up at the station, at least on weekdays.
Eastbound, as best I can tell car rental agencies in the area are all closed by 7PM.
Looking to do this myself in a few months, getting off the eastbound train, I decided only good option was an overnight stay at a nearby hotel, then rent car the next AM. Maybe others on this forum can come up with a better option?