I live about 10 + miles from Centralia, and been there a zillion times so my honest opinion..........Are 16 + guys congregating at one spot gonna cause attention............maybe? probably, but IMO nothing to worry about. There has been detectorists there before and will be in the future. There are about a half dozen homes still there and ya might see some cops pass through, but I don't think they will bother us.
PS: Some incentive..................found my first ever Seated Liberty (dime) coin at Centralia in the back yard next to a big friggin' tree. Never forget that one, was a 1891. But don't forget, this is coal country, and Centralia is sitting on hot rocks, so detectorist beware.