Request: Custom File Permission Settings

Hello!

We have the situation that our hoster activated settings so that the webserver is not the file-owner of any created file, it only belongs to the webserver’s group. Unfortunately, W3TC assumes to be the owner and sets its permissions accordingly to the cache files (644), leading to all sorts of problems and malfunctions.
Could you probably consider to add a setting for applying custom file permissions?
Or is there already anything like this? Or can you suggest a workaround? Changing server settings is not an oppinion.

Thanks in advance.