Access to the original source object passed with aaData.

I am feeding datatables using an array of objects as aaData (as opposed to an array of arrays). I am also using afnFiltering to do custom filtering. Is there a legal way to access

oSettings.aoData[iDataIndex]._aData

(the source object) from the function I push to afnFiltering? The reason I want this, is that inside my custom filter I would like to use a source property that does not target any column. Right now, if I want to respect that _aData is private and should not be accessed, I am forced to put a hidden column in initialization, so it can be available in aData array that is passed to my filtering function. What I essentially would like is a behaviour of the afnFiltering functions like the

fnCreatedRow( nRow, aData, iDataIndex )

in which aData is the raw object.

Does this make sense? Am I missing an obvious solution?

Thanks in advance, Bill.