Stop shipping plaintext. FiveSecured encrypts, obfuscates, and licenses your Lua resources so customers run your work without ever holding your source.
For those who want to use it in SP, there is a program called "Addon Vehicles Creator" that will auto create a bare bone DLC that you can then drag into the DLCPacks folder in the GTA V directory. Simply just put the meta files and vehicle files in their respective spots within the newly created DLC and they should be useable in game provided you did everything correctly.