I agree with Taylor, I'd rather not see any alterations to the game simply for fan service. I actually think it does interefere with the game, because there would be a whole room that's just there for the sake of a few backers, it's stuff that doesn't belong to the Ukulele universe, it belongs to the real world.
However, I think that there is a neat way of incorporating the backers in the game without changing anything to it.
Given that it's Playtonic, there'll probably be cheats in the game. I don't know how we will be able to input the cheats, but imagine if there's a room like the sand castle in Banjo-Kazooie where we can input letters for cheat codes. Why not make a sound like if we input the name of a backer in this room?
That's not intrusive as it basically leaves the game unchanged. Nobody but the backer himself would know his name and would ever think of trying to input it, so it would not interfere with the experience of other players. And the room would serve a purpose other than just fan service, since it would also be used for cheats.