I know that in Visual Studio 2013 and below there is an option to turn on/off automatic surrounding of generated code with #region
at Tools > Options >
I'd recommend delving into ReSharper templates. It allows you to specify whatever you would like in your template as well as creating a autocomplete as well.
https://www.jetbrains.com/help/resharper/2016.1/Templates__Index.html
You may want to look into CodeMaid at the Visual Studio Gallery. According to the description:
Reorganize the layout of members in a C# file to follow Microsoft’s StyleCop convention, or your own preferences. Automatically generate regions to match. Run on demand or automatically during cleanup.
From what I can tell, this may give you the feature to want.