For integration with issue trackers there is a "Global extension configuration" feature, implemented through a special repository "plastic-global-config". This could be extended as a way to offer server-global configuration of cloaked / ignored items, revision filetypes etc.

This would be an alternative to adding .conf files for all workspaces locally on each machine, under %LocalAppData%\plastic4.

(I was told this is already on the roadmap...)