Fame
Go ahead and name one famous tour guide you've heard of. That should pretty much answer this question.
Museum regulars or seasonal tourists may come to know you on a first name basis, but you'll never be tabloid-style famous. That's not necessarily a bad thing—how many movies have you seen where the historical character has Brad Pitt's chiseled jawline or Keira Knightley's slim figure? At least this way someone might actually confuse you for the person you're dressed as.