Call me charlatan cuz I just tricked Steam.
Alllllllright, I found a solution. So I have steam version and a single drive.
You have to trick Steam to think it has two libraries. To do that you create a folder in your main drive. Let's say C:\SteamLib2. Then, you open the libraryfolders.vdf file on an editing program.
What you want to do now is to add this line before the curly bracket closes.
"1" "C:\\SteamLib2"
Open steam and right click on DCS World. Go to the Local Files section and the Move Install Folder option should be visible now. Click on it and choose your new library. It will take a while to copy the files, but it worked for me.
Hopefully it helps! :)