Reading up on the modding discussing for EGM on the previous board, it seems like adding MP maps as N7 missions was not possible due to the fact that spawning enemies in MP used a different method than the spawning method in the campaign (if I understood the issue correctly).
As such, the MP maps may not be viable as N7 missions, but what if they were used in a manner similar to the Normandy Crash Site? A passive recovery mission, rather than a combat mission?
For example: Shepard can land on Firebase Rio after the battle is over, with the intention of finding a missing Alliance commander, or a vital data disc with crucial intel, etc. and taking it back to the Normandy. The maps could be sprinkled throughout the campaign and would function from a narrative perspective similar to a text based mission but far more interactive.
It would also respect lore, as Shepard would be visiting an MP location after the battle has concluded. (In the vanilla game, MP battles took place when Shepard was busy elsewhere).
Though I am not a modder myself, I wanted to share the idea and get thoughts on its viability as a potential mod if anyone has the capability or interest to pursue it.