As I understand the rules, you can have screen at some other memory than your main program (for example the default screen at $400 while the intro is $3000 - $3fff) and only the bytes wasted by your logo or other graphics would be counted, but you can't expect the rest of the screen to be blank! If the intro was linked with a game or something that memory would be "random" and you'd possibly get garbage on the screen
@MCM: RAM area will be counted as used from first used byte to last used byte in one block. But you are allowed to buffer the used area somewhere else at start and restore it on exit so it appears untouchted.