The first time I saw Stanley in person with the small standard body it looked like a toy. That is not to mention the size of his hands compared to the fingerboard (the whole bass, in fact)!
When I was deciding on neck dimensions for my bass, Mica told me the reason Stanley prefers such a small neck is economy of motion. She said he prefers to minimize the travel distance for his fingers, given the tremendous amount of travel they experience every night. I think the truly amazing thing is that those big old hands will fit into such tiny spaces to do such exceptional things...
Bill