Did Boaz Perform Customary Maamar?

I'll start with a Ruth-related etymology. Do you know that Oprah Winfrey, the talk-show host, is named for Ruth's sister-in-law Orpah? (as noted also by Al Gore on the previous post.) As Winfrey explains:

Oprah Winfrey: I was born, as I said, in rural Mississippi in 1954. I was born at home. There were not a lot of educated people around, and my name had been chosen from the Bible. My Aunt Ida had chosen the name, but nobody really knew how to spell it, so it went down as "Orpah" on my birth certificate, but people didn't know how to pronounce it, so they put the "P" before the "R" in every place else other than the birth certificate. On the birth certificate it is Orpah, but then it got translated to Oprah, so here we are. But that's great because Oprah spells Harpo backwards. I don't know what Orpah spells.

On to the topic described in the post title.

From the last perek of Rut:

ז וְזֹאת לְפָנִים בְּיִשְׂרָאֵל עַל-הַגְּאֻלָּה וְעַל-הַתְּמוּרָה, לְקַיֵּם כָּל-דָּבָר, שָׁלַף אִישׁ נַעֲלוֹ, וְנָתַן לְרֵעֵהוּ; וְזֹאת הַתְּעוּדָה, בְּיִשְׂרָאֵל.	7 Now this was the custom in former time in Israel concerning redeeming and concerning exchanging, to confirm all things: a man drew off his shoe, and gave it to his neighbour; and this was the attestation in Israel.--
ח וַיֹּאמֶר הַגֹּאֵל לְבֹעַז, קְנֵה-לָךְ; וַיִּשְׁלֹף, נַעֲלוֹ.	8 So the near kinsman said unto Boaz: 'Buy it for thyself.' And he drew off his shoe.
ט וַיֹּאמֶר בֹּעַז לַזְּקֵנִים וְכָל-הָעָם, עֵדִים אַתֶּם הַיּוֹם, כִּי קָנִיתִי אֶת-כָּל-אֲשֶׁר לֶאֱלִימֶלֶךְ, וְאֵת כָּל-אֲשֶׁר לְכִלְיוֹן וּמַחְלוֹן--מִיַּד, נָעֳמִי.	9 And Boaz said unto the elders, and unto all the people: 'Ye are witnesses this day, that I have bought all that was Elimelech's, and all that was Chilion's and Mahlon's, of the hand of Naomi.
י וְגַם אֶת-רוּת הַמֹּאֲבִיָּה אֵשֶׁת מַחְלוֹן קָנִיתִי לִי לְאִשָּׁה, לְהָקִים שֵׁם-הַמֵּת עַל-נַחֲלָתוֹ, וְלֹא-יִכָּרֵת שֵׁם-הַמֵּת מֵעִם אֶחָיו, וּמִשַּׁעַר מְקוֹמוֹ: עֵדִים אַתֶּם, הַיּוֹם.	10 Moreover Ruth the Moabitess, the wife of Mahlon, have I acquired to be my wife, to raise up the name of the dead upon his inheritance, that the name of the dead be not cut off from among his brethren, and from the gate of his place; ye are witnesses this day.'
יא וַיֹּאמְרוּ כָּל-הָעָם אֲשֶׁר-בַּשַּׁעַר, וְהַזְּקֵנִים--עֵדִים; יִתֵּן יְהוָה אֶת-הָאִשָּׁה הַבָּאָה אֶל-בֵּיתֶךָ, כְּרָחֵל וּכְלֵאָה אֲשֶׁר בָּנוּ שְׁתֵּיהֶם אֶת-בֵּית יִשְׂרָאֵל, וַעֲשֵׂה-חַיִל בְּאֶפְרָתָה, וּקְרָא-שֵׁם בְּבֵית לָחֶם.	11 And all the people that were in the gate, and the elders, said: 'We are witnesses. The LORD make the woman that is come into thy house like Rachel and like Leah, which two did build the house of Israel; and do thou worthily in Ephrath, and be famous in Beth-lehem;
יב וִיהִי בֵיתְךָ כְּבֵית פֶּרֶץ, אֲשֶׁר-יָלְדָה תָמָר לִיהוּדָה--מִן-הַזֶּרַע, אֲשֶׁר יִתֵּן יְהוָה לְךָ, מִן-הַנַּעֲרָה, הַזֹּאת.	12 and let thy house be like the house of Perez, whom Tamar bore unto Judah, of the seed which the LORD shall give thee of this young woman.'
יג וַיִּקַּח בֹּעַז אֶת-רוּת וַתְּהִי-לוֹ לְאִשָּׁה, וַיָּבֹא אֵלֶיהָ; וַיִּתֵּן יְהוָה לָהּ הֵרָיוֹן, וַתֵּלֶד בֵּן.	13 So Boaz took Ruth, and she became his wife; and he went in unto her, and the LORD gave her conception, and she bore a son.

Earlier I mentioned irregularities in the yibbum. After all, Boaz was no brother to Machlon and Kilyon (presumably), nor was that other redeemer, Ploni Almoni. Ramban suggests this is customary yibbum, not halachic, Torah yibbum. I mentioned this earlier in terms of Naomi's suggestion to Ruth and Orpah that they might perhaps wait for Naomi to give birth to another son, who would perform yibbum, which would be a problem of achiv shelo haya beOlamo as well as eshet ach min haEm (and not min haAv).

Interestingly, when Boaz does marry Ruth, there seems to be kiddushin as well. He states

י וְגַם אֶת-רוּת הַמֹּאֲבִיָּה אֵשֶׁת מַחְלוֹן קָנִיתִי לִי לְאִשָּׁה, לְהָקִים שֵׁם-הַמֵּת עַל-נַחֲלָתוֹ, וְלֹא-יִכָּרֵת שֵׁם-הַמֵּת מֵעִם אֶחָיו, וּמִשַּׁעַר מְקוֹמוֹ: עֵדִים אַתֶּם, הַיּוֹם.

10 Moreover Ruth the Moabitess, the wife of Mahlon, have I acquired to be my wife, to raise up the name of the dead upon his inheritance, that the name of the dead be not cut off from among his brethren, and from the gate of his place; ye are witnesses this day.'

Assuming he did not sleep with Ruth in the threshing floor (a fact about which I remain somewhat unconvinced, BTW, but that should be the topic of another post), he had not yet slept with her. How could he say he "acquired" her. This sounds like regular kiddushin.

Or later:

יג וַיִּקַּח בֹּעַז אֶת-רוּת וַתְּהִי-לוֹ לְאִשָּׁה, וַיָּבֹא אֵלֶיהָ; וַיִּתֵּן יְהוָה לָהּ הֵרָיוֹן, וַתֵּלֶד בֵּן.

13 So Boaz took Ruth, and she became his wife; and he went in unto her, and the LORD gave her conception, and she bore a son.

There are then three possibilities:

1) Indeed, this is mere customary yibbum, so sleeping with her without prior betrothal would be improper. He either performed betrothal here, or the right to perform betrothal, which was done later. Thus, she was a regular wife to him, and then they slept together. There was thus kiddushin and nisuin first, perhaps as described in pasuk 13.

2) I am misreading all this, or reading too much into this. He is making a formal "acquisition" that he is to be the goel, redeemer, and not the closer relation.

3) Later, Chazal innovate "maamar," a Rabbinic betrothal performed prior to halachic yibbum. Perhaps this is not such a new Pharisaic innovation, but was practice even in Biblical times, for customary yibbum, or if that is how they read Torah law, a practice even for halachic yibbum.