how to declutter interface and save functionality?

I have an open-source file uploading desktop app. At some point there is a step, where user needs to choose description fields for files he's about to upload. He needs to have three choices:

• Yes (I need that field)
• No (I don't need that field)
• Constant (I need that field, but it will be the same for all uploaded files. When this option is selected, you need to have possibility to write it.)

Here's my current approach with three variants. First one is using combo box, second one: radio button groups, third one: three state checkbox.

With 20 fields the interface is bloated with UI controls, so I'm searching for solution how to provide functionality above with more intuitive and less cluttered way.