have not added any characters or armies yet
how literally did you mean that? Some factions have to have at least leader or else no factions are technically 'alive'!

Sounds like you're on right lines for trying things, harvests events and disasters files can be empty and other tga's apart from map_regions and map_heights.tga can just be a plain colour.

Are you getting a map.rwm generated?

If all else fails upload the campaign folder and its data/text.regions names file somewhere, post link and I'll try and have a look.