Shaking the Nickel Bush, originally published in 1976, is the sixth book in the Little Britches series.
From the 2001 audio book:
Now 19-years old, skinny, and suffering from diabetes, Ralph Moody is ordered by his Boston doctor to seek a more healthful climate out West. Remembering his childhood ranching adventures, Ralph is delighted to strike out for new territory and prospects. Hustling jobs, and trying to find the means to follow the doctors orders, he becomes a Hollywood stunt rider.
With Lonnie, a rascal and friend, he camps out in the Arizona desert and "shakes the nickel bush" as a cowboy artist-sculptor. Lawyers and bankers are eager to buy his work as two move from town to town in an old Ford aptly named "Shiftless." But will Ralph ever reach Littleton in time for the 4th of July roundup?...
The Fields of Home
The Dry Divide