In my humble opinion, if this mod wants to become more than a curiosity, it needs to seek whitelisting and support from TWI--and not dither and wait on the matter either. Wait too long and the game might become too old.
I have no clue what is feasible, but the ideal scenario would be to work a little bit with TWI so that when the next patch comes, the mod will be whitelisted and working on release day. When the next free weekend comes, TWI can install it on the official servers that they open up. The hundred thousand or so people trying out RO2 during the free weekends would build enough critical mass for the mod so that it would be played on a regular basis.
The mod is loved by many but with only bots and maybe 3 or 4 other people to play with, no one is going to sit in a server for a few hours waiting for it to fill up. Its a catch-22. People won't join empty servers until their are other people to play with.
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If support from TWI is not possible then communication with the big server owners will be key. Talk to the big clans. The whole unranked vs ranked tab thing can be sorted out if several popular servers siwtch at the same time since they will visible on everyone's favorite server tab.