JamesYou obviously haven't had a lot of experience with blood stains !
Mass blood should not be cleaned in the first place. Certainly not with an extraction machine.
So what do you suggest Peter? A straw? a pressure washer?I can guarantee you that if the extracted blood stain is fully dry before you leaving that it wont come back even when you come back in 12 months to re-clean.By fully dry I mean, hand tool, extra dry passes, towels, hair dryer/air mover. If it comes back once you've dried it all it usually only needs a light going over with the hand tool then dry again.