TeamSite Search - how to exclude all files except DCRs

System

I want to only index DCRs. My DCRs do not have file extensions. From what I can tell, I would have to add all the possible file extensions that my users import (100 to 120 extensions) to the iw.index.binaryextensions entry in the search.properties file in order to exclude them. The problem with that, is that a user can import a file with an extension that isn't in the list and then, voila, it's indexed. Also, if they create a file without an extension, which is possible, then this also would get past.

Is there a better way to do this than by adding this large list and routinely checking the list file extensions on a periodic basis?