Please see notes in attached files. Search for "DA HACK" where notes are added to suggested changed parts along with reasons and benefits.

Hopefully self explanatory and a case of a "drop in" change. Look at "mapper.php" first.

Basically facilitating code hackers like me. A plugin would be best but don't think it is worth the effort on your part since usage is likely to be quite low with extra maintenance burden for you.

Basically what I use to give me flexibility with processing feeds.
Hope it gets a thumbs up!