Welcome Jogarman. You have advance quite a ways in the LMG course so you have considerable skills under your belt by now, so to speak. Just as you started learning how to strum rhythmically to a metronome, whole notes, half notes, quarter and so on-one- step at a time-so might you consider learning to sing along with your playing. Select a simple 3 or 4 chord song that you know well lyrically (or have the lyrics and chord chart visually close at hand) and go back to square one with your rhythm playing. Keep your strum playing simple, slow down and focus on the melody, hum at first if you need to, use the metronome. As you become more comfortable and familiar with integrating a third task while both hands are working their own actions, you can begin to advance to a more accurate tempo and advanced strum pattern. There is no fast track, just as there is no quick way to "learn and master" guitar but dedicate a small part of your practice each day to the task, perhaps at the end of your dedicated practice schedule. That said, I know some very skilled musicians who simply can't sing while playing, and it does become more difficult as the chord progressions become more complex. It is a learned skill however, so don't be discouraged if the challenge appears too daunting at first. Practice and patience is a virtue. Best of luck on this.
Greg