One of the things I did and I listed it in the "tips and tricks" topic was to simply copy my data folder to a separate drive, that is if you have the room. Most of the mods don't affect the Data folder unless it is changing a prefab. All the mods I am working on vehicle lighting wise do in fact. The other thing is if you have the STEAM version of the game then the files are always available. You can simply go to the LIBRARY tab of steam and right click on your game. Click on the word "PROPERTIES" Then go to the "LOCAL FILES" tab. On this tab will be a another button labeled "VERIFY INTEGRITY OF GAME CACHE..". If you click this button then STEAM will compare all files on your game and replace any that are bad or missing.
So you always have a plan B. Mind you that this process can take awhile and I have used it many times, because I love to mess with the files and have broken the game more then i have played it. LOL
The other thing to keep in mind is, when I created a copy of the DATA folder I found that even when I replaced a file that I have on the backup drive "D" for some reason the game seemed to ignore it and the file (example the one for the police_stw) never showed in game until I did the STEAM method listed above. I think that when you create a copy of the file that somehow it is TAGGED a copy and STEAM will not use it for fear that it is a torrent file. So just be careful using that method.
If you do run into an issue just feel free to post it on here.
Also remember that the way a mod works is it runs in place of the default EM5 files. So if one of my mods is for the tech_towcar (for example)
When you run the mod the following files are "CHANGED" in the EM5 Data Folder or another way to think of it is when a mod is selected those files take priority over the default EM5 files.
When the mod is deactivated all those files are effectively turned off or lowered in priority. The actual files don't change as long as the GAME INSTALLS THE MOD and the WORLD EDITOR WAS USED TO PUBLISH THE MOD. If you start copying and pasting files from mods into the game folder itself that when you run the risk of messing up your game..
Best of luck
Bill