Thanks to everyone for the replies / suggestions.
Roger: Brilliant suggestion about the friend to fret the A string for me. That will be his/her only job: fret that ONE note in that ONE song. Sorta reminds me of the guy in the Mighty Mighty Bosstones whose only job in the band is to dance by himself on stage.
Russell: Interesting thought which I hadn't considered, i.e., playing a "D7" form on strings 2-4 all on fret 2. So far I can't make the reach around to the A string with my pinky to get to either fret 2 or fret 4 (not without muting a bunch of strings anyway), but I'll keep working on it.
Phil: Tried that one also. This is probably the best way to minimize movement, but so far I can't do it without muting the high e. I'll work on this one too. FYI, the song is "Piano Man" (Billy Joel), which I'm playing in D. The A/C# goes directly to D. C#m doesn't work in that context.
Zurf: You proposed a similar solution to what Russ suggested, it's just that yours is the traditional lined up open A. Same issue; I can't reach the A string with my pinky yet, but with more dexterity it might be possible. You and Russ must have some amazingly long and flexible fingers.
auxi: You are absolutely right. Your suggestion (as well as all of the others) will work. I'll just have to practice in order to nail it.
Thanks again,
Nom