Another one of my innovative ideas!
As my forum is restricted to replies only I needed a way to enable similar content searches apart from title or message searches. Dead simple solution really. Create message only searches and use them as tags within the message - at the bottom. By adding these searches within the eng language file where the search warning is you have a tag search in place.
An example page with tags:
Search With Tags
I will just keep adding these tags as I go along.
Never know this might work for others too.