like skyrim
mod manager does.
Like you are already reading files from the external DBC folder for kits, you can have another folder in it for gameplay files,
give an option in CA or an external launcher to load and unload them.[This is not compulsory we can just rename the folder to not play with mods, this is just to make it convenient]
So whenever external files are loaded from that particular location, you can disable the leader boards like you have done for rookie level in career also online.
After playing, once i unload the mod files, CA can restart back with the unmodified original files with online and leader board enabled.
This is general idea ross, but i dont how feasible it is with DBC, if it is possible it would be great.