While I fully believe Naruto has his RSM, the mode he used was not RSM. The lack of pigmentation means little when he has not manifested a single TSB and his cloak does not have the main implication that he's using RSM, which is
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, not to mention RSM is more like a short jacket in appearance, while BSM is like a cloak, which resembles what Naruto used more,
and that Naruto has an all black design from his torso downwards in RSM, while this is not the case with BSM.
While I do hate this aspect of truth seeking balls, unfortunately he only lacks the truth seeking balls because he seemed to use them all up by the end of the war and the battle with Sasuke. Truth seeking balls (from what we've seen so far) can be lost if they either get destroyed or if they move too far from the user. Just look at Rikudou Madara. Once Minato warped away Madara's truth seeking balls, Madara never got them back. Even the anime's current opening just completely omits them when showing Rikudou Madara (while they simultaneously show them floating behind RSM Naruto, which proves that they did not just simply forget about the gudoudamas).
As for the cloak's design, the designs for the cloaks actually seem to change with both age and with clothing. Here is how I know that:
During the war, Naruto's BM and BSM had that epic jacket-like cloak to it. 2 years later in "The Last", Naruto went BSM in the battle against Toneri (and yes the guidebook that came with the movie confirmed that it was BSM and not KCSM). There was no jacket-like cloak, which proves that the modes' designs do change over time and depending on what clothes the user is wearing.
In a similar way to how the BSM design changed, the RSM design must have changed too. Keep in mind that unlike during the war (where base Naruto didn't have a jacket), hokage Naruto wears the hokage cloak. Therefore it makes sense that the RSM chakara would extend over his hokage cloak. That accounts for the length of Naruto's RSM cloak changing. As for the magatama and rinnegan symbol on his back, I don't know definitively why those aren't there.
The best theory I've heard about it was this:
Naruto is using RSM with just rikudou chakara and Kurama's chakara (and not all the other bijuus). Based on what the wiki said, the initial appearance of RSM is nearly identical to Naruto's base form, but it just has the eyes of RSM (this is the appearance that Naruto had when he kicked Madara's gudoudama). The cloak and the truth seeking balls come from Naruto drawing on the chakara of all 9 bijuus in addition to the rikudou sage chakara. The person theorized that perhaps the RSM we've been seeing for the past few chapters is just rikudou sage chakara + Kurama's chakara. That would explain why the cloak doesn't have the rinnegan symbol, the magatama, and the truth seeking balls. Of course, that is just a theory. It has very convincing logic though.
Anyway, if they had both lost rikudou chakara, then Sasuke wouldn't have rinnegan (as it requires rikudou chakara). If you say "Nagato didn't have rikudou chakara", then you'd be wrong. The rinnegan eyes themselves contain rikudou chakara just like the rest of the body. Therefore Sasuke does have rikudou chakara, and if his rikudou chakara didn't leave him, then neither did Naruto's.