I keep leaning towards construction. There's a lot of building in Reno, Las Vegas, the Sacramento area - northeast of the city, and going south, through the San Joaquin Valley.......Modesto, Merced, etc. In Nevada, there's a lot of construction south of Las Vegas too. Bullhead City, Arizona, on the river and border with Nevada is also booming.
In the construction industry there's a lot of jobs within that field - carpentry, plumbing, electrician, masonry, roofing, etc. There's excavation involving backhoes, dump trucks, and other heavy duty equipment. He could work in any of these fields having to do with construction.
Aside from construction, he could work for a trash-hauler, or be an independent trucker, landscaper, or drive a cement truck for small cement jobs (outside of the construction industry). He could also be an independent trucker, delivering goods from point A to point B.