But how do you play chords on a guitar, if you can't make this stretch?
I don't know, but he wants to play bass. Playing bass is more about time, note choice and nuance than physical limitations. If you can't make the stretch, get a short-scale bass. Learn to deal with the getting from one note to the other.
Drop the logistics. If you want to do it, you'll figure and work a way to do it.