I successfully added carriers and US and FAA carrier-based squadrons to all the fictional stock European campaigns. Unfortunately, the USN squadron decals will not show on the stock aircraft (for example: F-4B, A-4C, or F-8E). National and kill decals still work, as does the USNGrey series skins. While this is just a cosmetic problem, it's annoying because I can get the squadron markings to work on all the other stock campaigns.
Here is my campaign files for the 1962 European campaign. I had to convert them to text files, because it wouldn't allow me to upload them as ini files. All of the content is the same.
CAMPAIGNE1.txt
CAMPAIGNE1_DATA.txt
To answer your post:
-My version of SF2 is a merged install
-The loss of USN squadron markings is happening only on the three European campaigns
-The USN Squadron markings work just fine in Single Missions on the German terrain
-The loss of USN Squadron markings happens to both stock and 3rd party aircraft
-The squadron format in both campaign.ini and campaign_data.ini is exactly the same as the stock squadrons
-I used already existing squadrons where ever possible and added the squadrons I needed to the squadronlist.ini