Custom iOS folder icons?
No, there isn't a way to do this with the stock iOS (any version).

The only way you can do this, and I've never tried it but I've read about it, is by jailbreaking the device first.  

You've already discovered the workaround which is to create a shortcut to an app that's within a folder. 

Until Apple allows this level of customization, you will not be able to change the looks of folders.