They can start by tracing the route of Harvey Milk transporting the minor Jack Mckinley he was simultaneously acting as father/guardian to while sodomizing. It started in New York when Jack was just 16 and incapable of consent: a felony. It continued to California where Milk continued sodomizing him as a minor until he turned 18. All in violation of the federal MANN Act.
They could have sites "this is where Milk sodomized Jack, near the Yellowstone Park" or "this is where Milk made Jack perform oral sex on him at Yosemite". Stuff like that.