I just found something while poking around in the Campaign's.
There are MANY files that are identical duplicates (Common) in each Campaign like Harbors.mis for example.
I used WinMerge to verify that all these files were identical. (A lot of dead weight and not to mention keeping them in sync)
I edited my data\Campaigns\CampaignProjects\Total_Germany.pj file and made the following changes.
[Layer21]
LayerType=0
MissionName=
..\Common\Harbors
[Layer22]
LayerType=0
MissionName=
..\Common\ScriptedPortPlanes
Mission Editor 2 was able to successfully load those files for the total Total_Germany Campaign from the Common Campaign without any errors.
Using TDW_GenericPatcher_v_1_0_168_0 I have the option enbled to show all game messages and there were no error's while starting the game.
I started a new Career and the Buoy's and Scripted Planes were working in Total_Germany Campaign.
Removing all those Duplicated files would greatly reduce TWOS MOD size (disk space footprint) making it a faster download etc.
This is a easy change to all Campaign Project (.pj) files that can be tested/verified quickly.
-=[EDIT]=-
Here is some more info on a test I am running now.
Regards!
TheBeast