Well, the easiest way to drum up support for such a project would be the same as in the real world- demonstrate suspended animation followed by successful reanimation. If death were provably no longer inevitable and those approaching it could be credibly preserved until they could be restored even if they could not at present there would be an awfully large surge in investment towards curing the various conditions which tend to force people on ice up to and including general senescence.
My problem is mostly that FMPOV, Yuno and Noburi must be married within 7 days, and it is expected that a Hagoromo officiates.
How do we thread the needle on this, then?
The only option likely to work in that timeframe is to either tear or at least temporarily disrupt Hag public authority enough to get away with one or no side of a schism and/or scandal officiating at the moment.
So, potential assistance to reformist elements within the Hags to drive a wedge. That's unlikely to be fast enough, but the beautiful thing is that we don't need an actual insurrection, just the leadership to credibly believe that one has been cultivated to be imminent. They know that four clans, including the spooky thinker clan and the one they are gravely indebted to have been cross with them since the vote and may well have been exploring their internal divisions the whole time. It's a lot easier to make them think that a more liberal element has been systematically organized and turned than to actually do it, then allow (or in turn, fake) their overreaction to make it at least publicly appear to be a reality.
Then there's the potential to make them think that this was a Hyuuga trap to get them back into debt bondage, or a Minami trap to split off a portion of the clan, or to suspect both while the sky falls around them.
All it takes is one single associated priest being fooled into officiating in the hopes that it will make the chaos stop, or the general public doubting any current Hag faction having the legitimacy to do it at all.
We have Mari, Ami, ISC, and Jiraiya's notes. It seems as if they might be able to provide quite a few grenades to toss into intraclan politics.
-or, we just murder Neji and frame the Minami.
Asking Hidan to officiate remains an option. He's technically not an enemy of Leaf, and while it's not quite the message we want to send, it's quite a powerful one.