I've created this new unofficial information topic, to avoid cluttering the "official information" topic, as we are now within an octave of the consecration of the bishop-elect, and I would prefer not to interfere with the efficient spread of as-yet unknown updates or other changes to the event's official information.

I want to do SOMETHING to suggest I'm Catholic, not just a well-dressed Lutheran.

Ah!  Thank you for the clarification.  So dump the potentially classy-but-obscure heraldic & other graphic art, and get a shirt printed with the blunt motto (in the Arial type-face if you must):

• "Martin Luther: 500 years of heresy: 1517--2017!  Enjoy eternity in Hell! "

Whaddaya mean, it ain't oecuмenical, like Nostra Aetate urges?  I  did  express my wish that Luther's followers "enjoy" it, didn't I?  Picky, picky, picky!   Even so, it might be prudent for each wearer to freshen  martial-arts skills before donning this shirt at the previously identified Protestant-infested lodging site.

Remember, protestants and atheists get dressed up for conferences and special events too. So just a suit & tie and modest dress will NOT give you away as a Catholic.

What!?   I take it, then, that you don't own a red tie that's decorated with illustrations of historic papal tiaras?

Or even a "Texas-sized" belt buckle whose featured casting is the emblem of Vatican City?

[....] Or just an illustration of the broad-brimmed tasseled heraldic [ecclesiastical hat ] [...], or failing that, a mitre, either 1 also bearing the date of consecration. [....] untranslated from the Latin, the better to befuddle the Protestants and assist recognition by fellow traditional Catholics

As best I can determine, albeit from classically-oriented Latin reference works (instead of ecclesiastical Latin), this is "May 11, 2017":

    ante diem quīntum Īdūs Māiās
    Annō Dominī MMXVII [‡]

Overly literally: " before   the fifth day  before   Ides (of) May
(in) the Year (of Our) Lord 2017"

Customarily abbreviated thus:
     a.d. V. Id. Mai.
    A.D. MMXVII

Where the 1 word-length underscore above indicates movement (of the translated word "before") by deletion then insertion.

From the perspective of classical Latin, the small letters shown in the Latin above should be rendered in small-capitals (or if lacking the latter, then ordinary capitals), because the only letters that classical Latin had were capitals, which are what modern readers & writers often call upper case letters; invention of lower-case letters was quite a few centuries away into the future.

Feel free to compare my book-dependent translation above with the signature formalism of traditional papal encyclicals.  I simply haven't had the time to do that yet.

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Note ‡: Latin vowel lengths are marked to assist confirmation that presentation uses the proper inflections; abbreviations would not use them.  All declinable words are in the accusative case (e.g., no genitive); why that's so is a mystery to me (and not what I drafted), altho' it might be "progress toward (something)" (or even an extreme example of words used as appositives).  I'll call it a Latin idiom and try not to lose sleep over it.  "Īdūs" and its modifiers are always plural.  So it might be prudent to go with the abbreviated Latin date, which not only has the advantage of avoiding all[/] of the inflected endings (and explanations for the surprising ones), but also was a straightforward table look-up in a reference book for Latin.