Some artists are following Mr. Trump on the road. Last fall, David Gleeson and Mary Mihelic, who work as the t.Rutt collective, bought Mr. Trump’s old campaign bus and have been driving it around the country, stopping at rallies. They replaced his slogan “Make America Great Again” with “Make Fruit Punch Great Again” on their vehicle, and have encouraged people to pelt it with juice, in the hopes that it would help “process the emotion that was clearly getting ready to be stirred up in this campaign,” Mr. Gleeson said.

Image Mr. Whiteley dressed as a clown in Green-Wood Cemetery. Credit... Molly Krause Communications

Both Trump fans and opponents have been angered — “They don’t understand why this bus is art,” Ms. Mihelic said — but the artists have also had positive conversations. “We’re very hopeful that art in this kind of absurd environment is useful,” Mr. Gleeson said.

Creating the gravestone was not the first time Mr. Whiteley had taken on Mr. Trump in his work. In February, he even dressed up as Mr. Trump and, in the WhiteBox gallery, staged a routine with another artist, Rebecca Goyette, dressed as Sarah Palin — a performance that his interrogators this week were aware of, he said.

They also asked him about what books he was reading, whether he owned a gun and whether he attended presidential rallies. “Luckily, I think I passed all the marks that they needed to see,” Mr. Whiteley said. “I did not fit the profile” of an assassin.

Christopher Stout, who shows Mr. Whiteley’s pieces in his gallery in Bushwick, Brooklyn, said he was “absolutely unsurprised” when Mr. Whiteley described the gravestone idea to him last year. (The project was financed by an independent collector.)

“It thoroughly fits the canon of his work,” Mr. Stout said. Nonetheless, Mr. Stout advised Mr. Whiteley, a founder of the Satellite art fair, an alternative to Art Basel in Miami Beach, to consult a lawyer. (The artist has since engaged the civil rights lawyer Ronald L. Kuby.)