Finessing the V Chord in Slide Melodies
If you’re slick, you don’t actually have to change positions for the V chord in the 12th-fret position, though it’s still important to know how to change positions for the V. All I’m saying is that there are ways to use the 12th-fret position to play ideas that will work well over the V chord.
The best way to understand this is just to hear and play an example. Take a look at Example 14—note the quick turnaround from I to V and back again in measures 3 and 4, which calls for some rapid thumb work.
Why does this work? Well, when you stick to the notes at the 12th fret like this, you’re basically playing notes from a G-major scale. That still sounds all right over the V chord because the V chord and the I chord are both in the key of G, and both chords are built out of notes from the G-major scale. Also, when you’re passing fairly quickly through the V chord like this, the sheer melodic strength of repeating a figure in the G-major scale over both chords will carry you through. Besides, just listen to it. It sounds good. Sometimes that’s enough of a reason.
Excerpted from Acoustic Guitar Slide Basics