Yeah, the tower system works pretty well in my opinion.

The guild system is the real issue for why the spam recruiting still exists. It may still exist if you went with the "they can't join a guild for a day if they leave/are kicked" since you could still kick and recruit noobs as a guild and you would remain unaffected. The players would be, but your guild wouldn't be. You could also have the players use noob accounts(much more difficult, but still possible.) I would personally like it to where the guild is restricted as to how many recruits It could have per day. Maybe "your guild can only recruit 5 members per day" or something similar. Probably some issues with it, but I think it would be a good solution for not impeding social guilds while also knocking back the spam recruiting.

Or you could just use this idea. How guilds would change based on their distinction is beyond me.