When deleting a page with sensitive info make sure to use an edit summary, otherwise the default is to include the first line of text from the page. That causes some of the info to remain visible in recent changes and the deletion log even though the page is deleted.
Never make the oversight request on wiki because that draws attention to the libel, personal information, or whatever is being oversighted. Go to #wikimedia-stewards and type "@steward oversight en-wv" to get their attention. The bot will list the stewards in the channel. When one of them responds, use private message to tell them the page and/or edit comment that needs oversight. You can also request that a username be deleted. This might be needed if the username contains a personal attack, for example.
Since the above was written, revision deletion was enabled, which allows custodians to selectively delete revisions, revision usernames, and edit summaries. With this, oversight is rarely needed. Oversight will hide material even from custodians.