That would likely be impossible, at least in the later chapters. Perhaps if one stays in one of the earlier chapters and have 500+ scouted provinces, but I still doubt that.I love the idea of an AW to cut negotiating costs. I think there should have been such an AW released long ago. I fight almost exclusively so I wouldn't benefit so much from such an AW, but there seem to be so many AWs and buildings that help military, but there aren't so many that can help someone negotiate to a similar extent. I haven't done any calculations and I could be totally wrong, but I doubt there are even a handful of cities that negotiate their way to the top 30 in a tournament each week? It seems there should be something to make the non-military path a bit more equal. Please let me know if you are someone who frequently negotiates to the top 30. I'd like to know if I am way off base on my assessment of the disparity between fighting and negotiating.
As for the later chapters, just look at negotiation costs per single encounter. To be in top 30 you will need to go to provinces 30-40+ at least. A single encounter there (not even the whole province) in chapter 15 can easily cost several dozen Ks of regular goods. You simply cannot have enough production to make it sustainable, even with max number of expansions and all boosts.