I love this. I fell in love with Elvis in 1970, when I was six. It's never gone away, and I've spent the intervening years listening with passionate intensity. What I love about this song is that Neil Young is obviously steeped in the detail too - the opening scene of Love Me Tender, ploughing the field; performing on a flat-bed truck in Loving You; the blue-haired lady in That's The Way It Is. It's genuine, not generic.
Dylan also sings about Elvis in Went to See the Gypsy if you want another example! But that's a bit more mysterious, as it describes meeting Elvis on tour. There is no record of this, but it's similarly convincing in the mundane detail.