Preston Nichols and Peter Moon's The Montauk Project: Experiments in Time (1992) described Camp Hero's SAGE radar dish driving a Montauk Chair that amplified psychic Duncan Cameron's mind, opening a time tunnel to 1943 and to the Eldridge. Camp Hero is real; the radar dish still stands; the experiments have no record, budget line, or witness outside the books.
The darker stratum: runaway boys allegedly kidnapped for chair experiments, a creature summoned from Cameron's mind that smashed the base in 1983, and time refugees still walking. The lore directly seeded the fictional town of Hawkins: Stranger Things was originally titled Montauk.
A speculative defense: the SAGE dish operated at frequencies later studied for psychoactive effects, so the story is a corrupted memory of real electromagnetic research, Montauk as the unconscious of the cold war, dreaming in conspiracy.
When an author concedes the story may be invented, why does the bunker underneath stay real?