Here's the text as George Milburn printed it in The Hobo's Hornbook, my copy published by Ives Washburn, New York, 1930).

THE BIG ROCK CANDY MOUNTAINS

One sunny day in the month of May
A jocker he come hiking;
He come to a tree, and "Ah!" says he,
"This is just to my liking!"

In the very same month on the very same day
A Hoosier's son came hiking;
Said the bum to the son, "O, will you come
To the Big Rock Candy Mountains?

Chorus: "I'll show you the bees,
And the cigarette trees,
And the soda-water fountains,
And the lemonade springs
Where the bluebird sings
In the Big Rock Candy Mountains."

So they started away on the very same day,
The bum and the kid together,
To romp and to rove in the cigarette grove
In the land of sunny weather.

They dreamed and hiked for many days,
The mileposts they were countin',
But they never arrived at the lemonade tide
And the Big Rock Candy Mountain.

The punk rolled up his big blue eyes,
And he said to the jocker, "Sandy,
I've hiked and hiked and counted ties,
But I ain't seen no candy.

"I've hiked and hiked till my feet are sore,
I'll be God damned if I hike anymore
To be a home guard with a lemonade card
In the Big Rock Candy Mountains."

Milburn's introduction says:

This song provides some excellent samples of tramp fantasy. In many small cities and towns, the children of poor whites use the railroad yards as their playgrounds. From these urchins the jockers sometimes recruit their road kids, and to entice them they tell them roseate tales of tramp life. These fabrications are known as "ghost stories." To home guards "The Big Rock Candy Mountains" may appear a nonsense song, but to all pied pipers in on the know it is an amusing exaggeration of the ghost stories used in recruiting kids.

I suspect the omitted line from the Lomax text contained a somewhat crude description of the sexual act performed on the punk by the jocker.

Sandy