Hey. I'm trying to transfer the features of the native factions from the Warpath Campaign to the original native factions from the Grand Campaign. I've had limited success and hit a lot of what appear to be dead ends... I wonder if anyone could suggest a working method?

So far I've tried three main methods:

1) Changing the subculture of the GC natives from "sc_tribal_american" to "sc_tribal_playable".
Problems with this method have been:
It's impossible for the resulting factions to leave navigate away from the American theatre on the map.
It's impossible for the resulting factions to construct buildings; seemingly the Grand Campaign building slots don't accept Warpath buildings.
The resulting factions have no Policies panel and no Ministers panel in the Government screen.
There are probably other problems, too - this method is too flawed for much investigation to be worthwhile, unless the major issues can be overcome. One that occurs to me is that Scouts and Shamans might not spawn, but maybe I'm wrong. There are also issues with the tech tree, which needs to be replaced with the Warpath one. This doesn't happen using this technique.
Required solutions:
Force Grand Campaign building slots to accept Warpath buildings.
Allow the sc_tribal_playable subculture to move between theatres.
Allow the sc_tribal_playable subculture to access the Ministers and Policies panels.

2) Changing the tribal_playable buildings and nan_* units to allow them to be built/recruited by the sc_tribal_american subculture (and the relevant military group).
Problems with this method have been:
The primary problem is with the buildings. I used the building_culture_gov_type_variants table to replace the tribal buildings with their tribal_playable countertypes. Again, there are issues with buildability on the Grand Campaign map; aside from this there are 'phantom buildings' without names or descriptions. The effect of this method, when it succeeds, seems to be that the tribal_playable buildings are simply added to the tribal buildings in the list of buildings available to the sc_tribal_american subculture.
Required solutions:
This technique seems to be a dead end - it might be operable by modifying the CA tables instead of adding player-made tables.
Replacing the tech tree.

3) Changing the effects and units_allowed lists of the tribal buildings to make them identical to their tribal_playable counterparts.
Problems with this method have been:
This method is fairly successful. The primary problem is finding a way to replace the default Native American Grand Campaign mines with the Warpath mines (the GC ones have no model on the campaign map) and adding the Warpath Native sheep farms to the Grand Campaign. There have been some minor problems that were probably more a result of my clumsy implementation than anything else. Another big problem is the tech trees: the new buildings don't provide access to native techs (NB, exclusively native techs. You can add the Warpath tech tree to the existing one, but can't switch to it in campaign mode.)
Required solutions:
Finding a way to add the sheep farms and mines.
Replacing, rather than adding to, the tech tree.

So, can anyone suggest any other methods? Is there a confirmed method? Any help will be appreciated. Thank you!