Can you meditate along with the guitar? Many years ago I learned a simple way of meditating which is to breath in for 5 seconds hold and breath out. Each time trying to listen to my breath. This activity of concentrating on the now helped me to focus when I had to go through a tough time with life and work. This is not exactly emptying your mind but focusing your mind on something as simple as breathing.
Recently, I taught a student for over two hours and I thought why not meditate while bull dozing through finger exercises with my student. So I played a simple G major chord, playing every 6 strings in 2 bars of 4 count. At first, I was rather sceptical about it. So it went, G.. B.. D.. G.. B .. G .. 3 and 4 and ... so I breath in for 4 counts and breath out in 4 counts. Before that my mind was rather cluttered with a client that in my sideline business that was being rather an idiot of the first degree. Here I have a student paying me to teach but my mind was somewhere else.
Surprisingly after 4 rounds of doing that, my mind cleared up and the dust settled in my head. Of course we did more than 4 rounds of playing the G chord and more it went the more enjoyable I felt just practicing along with my student. Why not give it a try?