Tried this and found out that even if you can do that, you will have to arm the plane manually in the mission editor or at the beginning of the mission (if you're not airborne yet...). The conversion erase every loadout though.
It doesn't work for the paid campaigns.
And for some reason, I won't be able to convert a campaign at all. Though, that one just simply doesn't appear ingame in the folder. Don't know what to modify to make it working. Not the fault of the mod, surely have to change something or implement the *.cmp file, still didn't found out what.