I'd be into it.

Ben, you are quite correct with your concerns, whether focused upon the “license” of applying harmonic accompaniment, sung or played, to the Preface/EP/Collects etc., or the (to my knowledge) infrequently used Haugen (Four Freshmen) setting (there were others as well.)
As one of the young lions of liturgy, however, I urge you not to allow yourself to twist your own knickers into knots over every detail of liturgical praxis. I know this may sound a bit like “heresy,” but we mustn’t let legalistic myopia occasionally prevent us from appreciating the forest while diagnosing the bark of a single tree.
I’ve worked with celebrants in the past who chanted the preface note for note from the Sacramentary, but insisted that they needed accompaniment to stay in tune and in key. -That’s easily done with a “i-VII-v-IV/gm-F-dm-C” chordal scheme, for example. But the issue is, do you challenge the vicar with the GIRM opened to the prohibition page, not knowing whether on Monday morning the pastor will back you or wash his hands of you, or just discreetly undergird his chanted preface, no harm no foul. When those occasions were on my plate, I have to conclude the Lit. Police were on call busting a Clown or Puppet Mass elsewhere, and God didn’t mind because I didn’t get crisped by a lightning bolt.
Lesson (not moral) of the story: choose carefully which hills you want to fight for and perhaps die upon.

No argument to be found here, my good collegue! Nor do I wish to impose my will against the observance of any law, I was merely illustrating a "rock and a hard place" scenario for Ben wherein the solution had no "casualties" and the odor of the camel's nostrils eventually gets transferred.

I thought it was kinda Funk-y (pun intended, not the mood though) when, years ago, a certain music mover in the (then) newfangled Mass music of yore sang everything (yes, everything) at a Mass for an otherwise forgettable workshop, accompanying himself on a guitar. I shuddered and wanted to shutter my ears.

Clearly this is proof of the superiority of the EF, where this would be an impossibility for the celebrant, whose hands are otherwise engaged making a myriad of signs of the cross over the gifts.

On the other hand, perhaps each individual celebrant in this photo could sing their own Mass independently, but in harmony with the rest:

I would laugh hysterically. I've found that people who employ those sorts of ideas don't respond to constructive criticism anyway...so laughing at them at least makes them understand that people don't just disagree with them...they think they're ridiculous.

When a priest approaches me, asking me to accompany something, I say:

1) "I don't have music."

2) If he gives me music, I bug my eyes out and say "I can't play THAT!" Then usually play a virtuosic postlude...

This is one of the most strongly-worded rules regarding music, I seem to recall. I have no idea what the rationale is, but I try hard to follow it at all times.

Charles in CenCA ... I have! This particular Mass, celebrated in the evening at the close of the workshop, was more of a Virgil [sic] Mass for what, I suppose, was intended to be the new wave in the C [sic] of things to come. Anyway, it was not the sort of Funk that would have pleased very many who read this forum ... N(ot) P(leasant) M(usically) to me at all.

This was neither a Great nor a Swell idea, a fact of which I am Positiv, and I'm just glad we are finally beginning to shed the heavy Bourdon of this sort of stuff that isn't worth a tracker's action anymore. A priest singing a folksy setting of the Eucharistic Prayer while accompanying himself on the guitar just isn't a good Mixture, for it strays far wide of the Principals and Foundations upon which the Mass is based. I apologize for any MeanTone Temperament that I might have displayed in getting this Wind off my Chest. I'll Stop now before someone with more Ranks in his/her Cornet hits a General Cancel on this Corno {sic] Paean.

This conversation needs to be swept away by an unda maris. The shutters need to be closed on it - shudder!

Chuck in CenCA ... who would ever stoop Solo as to Bombarde you with crashing Zimbelstern his keep? But it did bring Tierce to these eyes to go the extra distance to get the 64ft Resultant.

Love the photo Adam!

I dunno, Mum, Wid-or someone else would have to GATHER a whole big Messie-an' lots of performers from all over. What if one of us had a Lang-lais-over Bach in Irving TX or Berlin, or worse, if we stranded an American in Paris? A pilot just can't Landini old place. Would we have to Partch together some sort of "Hello Dalli-" played on a piccolo in the interim? What if Chuck goes into Haydn somewhere? I know I couldn't just Lasso up talent, then Chopin up the routines Properly, I just couldn't hocket. Could you just walk up and Telemann "You're on in two, Guido, Handel it!"? "Oh, what a suite Delius youse givin' me, I's red all over breakin' out in'Ives I is!" And what if someone Souza's over intellectual property saying we violated copy Rites of Spring-time for... O Woz-z-'eck, who cares? I'm Giffen up this responsibility to you, MACW. I'm gonna Steal Away to Venice and then "rock" climb up Monte Verdi!

Gotta go to church now.