Greendeath,
have you added the text file
your_campaign_folder_name_regions_and_settlement_names.txt
into data/text (or BI/data/text - if using BI) if you haven't added new province names this can be a renamed copy of
imperial_campaign_regions_and_settlement_names.txt
(or barbarian_invasion_regions_and_settlement_names.txt)

missing this file is what normally causes crashes on selecting campaign. Map related crashes normally occur after you have selected the faction.

I think you can get away with plain black map roughness and trade routes so long as they are the right image size.