Here's my little addition to this topic.
I understand to run Prim+ DLC on Valhalla map, I must select map: custom. Then set the TC to 111111111, then set MapID and ModID to 504122600, and then check Custom Launch Parameters.
Will the the launch parameters override the game.ini file; and anything special I had changed within "Modify Server Configure" have to be typed inside that launch parameter box negating the need for the modify server config feature? If I do not type my settings into that box, will they load?