When Post Malone decided to go country, he did it in a big way. Other pop artists who’ve plotted country crossovers have done so humbly, usually after their sales have started to slip. But that’s not the style of the man from Grapevine whose driver’s license reads “Austin Richard Post.” He was still at the top of his game when he announced this year that he’d follow a series of one-off performances of classic country covers with a full album of original twanged-out material. As he started dropping singles for his country crossover, though—ostentatiously titled F-1 Trillion, with album art featuring a vintage Ford pickup plummeting directly into the Salto del Nogal dam, in the Mexican state of Jalisco—a kind of humility crept into what Malone…