Watch the Harmonics & Bass Part online guitar lesson by Dmitry Lisenko from Percussive Acoustic Bass (Foundry)
Here it's important not to rush and play the piece softly. Hold the low note, and while it's sounding, play a harmonic so that both note and harmonic sound together. That will create the illusion of two instruments. Don't rush, and pay attention to your low notes, make sure they sounds all the time.