I've talked about my stress-free hymn arrangements in a similar context on this forum, I think. But what I do is select some hymns that are appropriate to communion -- hymns referring to communion, such as "Let Us Break Bread Together," or those reflecting on the crucifixion or the passion of the Lord, whether formal hymns or dignified gospel tunes, never anything tacky or overly sentimental.
I set up several pistons with quiet sounds, celestes, soft flutes, and so on, along with some contrasting colors on the other manuals, including the softer solo reeds. I practice playing each hymn in a variety of improvised styles, going from SATB on one manual, to soloing out the melody on a second manual, then trying not-too-jarring re-harmonizations and mildly exotic chords and dissonances.
Since it's hard to know exactly how much music will be needed, I decide on different places where I can end if needed, or brief repeats that can be taken if only a few more seconds are needed.
Since I will have rehearsed all this until I'm comfortable with it, I just relax during the time of communion and play the hymns with whatever variations come to mind at the moment. It usually works out well and folks are generally appreciative of the quiet and reflective music that enhances the spiritual mood.
One thing I'd never want to play for communion would be a difficult piece that would stress me out and make me uncomfortable. This is one of the few times in a Baptist church when the organ plays alone for an extended time period.
John
Rodgers 890 at church.
Baldwin D422 at home.
Scads of old organs in the shop! H E L P !!!