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I really don't believe it's worth the hassle, but since you want help and not my opinion, here's my 2c
1st: Smarty allows you to filter/change/add stuff to your output easily (check my OldTimes theme, it removes img tags), is easier to understand than plain PHP and can be hacked in themes and/or templates
2nd: you don't want to hardcode background colors or to add the copyright text to your actual data in DB (you'd be the most annoyed by that
)
So I'd go for a theme based solution (because themes can deal with BG colors), but you might need to add "clues" to templates...
Do you have a test server ready?