Eidei Mesirah/Chasima Karti

When it comes to the giving of a get (divorce document) there are two general opinions quoted in the gemara in the beginning of Gittin. R' Meir holds eidei chasima karti (the witnesses who sign the get create the get) whereas R' Elazar holds eidei mesirah karti (the witnesses who watch the giving of the get from the man to the woman create the get).
The Rishonim argue about what exactly R' Elazar means. Acc. to Tosafos in Gittin 4a, R' Elazar holds only eidei mesirah can create a get, and a get with signatures is no good. The Rif disputes Tosafos and holds that even eidei mesirah are kores (create the get). There is a machlokes within the Rif as to what exactly he means. Acc. to the Ramban, the Rif means to say that in order to make a get effective one can use either eidi chasima or eidei mesirah; in other words there are two ways to be kores a get. The Ran, however, offers a different explanation. He holds that even acc. to the Rif there is only one way, technically speaking, to create a get. That is through eidei mesira. However, if a get has eidei chasima on it and that get is in the hands of the woman, so those signatures have the halachic status of eidei mesirah. This is because there is now an annan sahadi (halachic status of eidus) that the get was given from the man to the woman, for how else is the woman holding a signed get in her hands? So there are essentially three shitos within R' Elazar- 1. only eidei mesirah karti 2. either eidei mesirah or eidei chasima karti and 3. really only eidei mesirah karti, just that eidei chasima can act as eidei mesirah. (See dafei harif daf 47 in detail with the nosei keilim there for more.)
Now, if you haven't lost me yet, here is where it gets interesting. Within R' Meir's opinion Tosafos makes an interesting comment in the name of Rabbeinu Tam. He says that acc. to R' Meir you certainly would need eidei mesirah also (in addition to eidei chasima) because otherwise the gerushin, the divorce itself, would not be effective, because of the rule of ein davar shebervah pachos mishnayim (all ceremonies involved with ervah issues must be done in front of two people).
So, in effect, Rabbeinu Tam is saying, that acc. to R' Meir one needs both eidei chasima and eidei mesirah. The question is, does the Rif agree with Rabbeinu Tam's opinion, within R' Meir, that you need both eidei mesirah and eidei chasima? The answer would seem to be no, because if R' Meir says you need both types of eidim, and R' Elazar is saying even eidei mesirah karti (as well as eidei chasima) so they wouldn't really be arguing! Why would the Rif go out of his way to say the acc. to R' Elazar even eidei mesirah are karti, and not mention anything in R' Meir when a very similar point could be made that both are really needed? It would seem then that the Rif disputes Tosafos and holds acc. to R' Meir that eidei chasima alone are good and you don't need eidei mesirah. How then would one fulfill the din of ein davar shebervah pachos mishnayim acc. to the Rif, if you have no eidei mesirah?
This question leads many achronim to suggest a proof for the Ran, that the eidei chasima become eidei mesirah, for if not - how do we fulfill this din of ein davar shebervah pachos mishnayim??
However, I heard (or maybe saw) in the name of R' Soloveitchick that in fact the opposite is true. It's the Ramban's opinion that makes perfect sense and the Ran which is difficult. The Ramban would, in fact, agree that acc. to R' Meir who holds the eidei chasima create the get, so the get is a good get, it has a shem shtar, and memailah it creates an annan sahadi that the get was given to the woman and halachically we have eidei mesirah. While this makes sense in R' Meir, this would not make sense in R' Elazar as the Ran is attempting to state. Acc. to the Ran within R' Elazar, eidei chasima do not really create a get, yet, at the same time, they can create an annan sahadi and create eidei mesirah which then creates the get! The whole thing is circular, if it doesn't have a shem shtar... how does the annan sahadi get created! Only in R' Meir it makes sense because the eidei chasima create the shem shtar and then the shem shtar can act as eidus to the mesirah and create the gerushin. This point the Ramban could in fact agree to, but he would still dispute the Ran that such logic could apply to R' Elazar's shitah.
I thought to answer for the Ran as follows. R' Soloveitchick had a fundamental principle (see Sefer Eretz Hatzvi by R' Schechter for more on this) that the machlokes between R' Meir and R' Elazar is only by shtarei kinyan - documents used to create some type of transaction or "challos". However, by shtarei raayah (documents made only as a proof of a transaction) forsure one would use eidei chasima, because otherwise how is the shtar a proof?? (Rashi on daf 3b in gittin implies not like this, but R' Soloveitchick explains it away by saying that even a shtar halvaah might be a shtar kinyan on the shibud nechasim.)
If this is the case, we can suggest in the Ran that although the eidei chasima are not effective to make the shtar a shtar kinyan, meaning a get that could effect a divorce, the get still has the ability to be a shtar raayah on the divorce. If so, there is a shem shtar and when the get is given we have an annan sahadi. That annan sahadi then circles back to create eidei mesirah and make that very same document effective as a get to divorce the woman! This gets us out of the problem because now the get has a shem shtar before the annan sahadi is created.
One final note: there is a hagahos mordechai at the end of kiddushin (570) that brings a Teshuvas R' Avigdor that if a shtar is meant for kinyan (like a get or shtar kiddushin) it cannot work as only a raayah. Meaning that R' Avigdor holds there can never be a get that is only a raayah... it must have also functioned to create the gerushin if it intends to be a proof. My above explanation in the Ran would have the Ran opposing this because the get is acting soley as a shtar raayah in the beginning. This isn't so bad because the Shiurei Rav Shmuel already suggests that Tosafos disagrees with this R' Avigdor because Tosafos says that within R' Elazar the eidei mesirah create the get entirely and nevertheless one can have eidei chasima only as a raayah.