Well, that would work. Although, we will need to think about if it fits will with the Hyrule universe and if it fits well with our story. I think they'd fit into Hyrule well enough if there was more emphasis placed on them, and more about them was exaplined. However, this would require shifting focus onto them more. I think it'd be a little awkward trying to put something that kind of needs explanation and backstory into this relatively small part, when the rest of the game focuses on different characters.
I say that the horsemen would need more backstory and explanation primarily because this isn't the first time the triforce has been threatened- in fact, Ganon has gotten at it at least once in OoT, and gotten pretty close in other games. If there were horsemen whose sole purpose was to protect the triforce from evil, they've been doing a shitty job. We'd need to 1) introduce these guys into the lore at the beginning of the game, 2) explain why they're there, but not to Link, because that would tell him that Ganon is evil, and 3) explain why they didn't do this before when Ganon went after the triforce.
Personally, I think this is distracting from the main game.
Therefore, I'm still in favor of having either Zelda disguised as Shiek, another Shiekah (working for the shiekah elders, not an evil one), or Maple be against Link, this character's goal is just to get the cogs before Link does. I think this would be simplest and most in-line with the plot we've already established, bring up the fewest problems.
But, if you guys have a reason why these options aren't as good, an explanation for the horsemen that meshes without questions, or another idea, I'm not in charge, I'm just argumentative :p
Niek, you ninja'd me while I was typing. I still say basically the same thing, but will add that I think for an antagonist that would build the plot the most, we should have Zelda, disguised as Shiek. The royal family doesn't take her seriously or believe her when she has a feeling that Ganon isn't who he says he is. She wouldn't be very confident in herself at the beginning either. She would just spy on Link at first, and warn him to be careful who he trusts, then show up later and fight him for his cogs. This idea is far from developed, though...
And I still think that if Maple is also looking for the cogs, she should be the antagonist. Mainly because we don't need three different parties trying to stop each other from getting the cogs. If we don't use Maple, I feel like it might be a good idea to readjust her story.
I think if Maple isn't the antagonist, then she could have an awesome part in JUST the Goron section of the game. Her story can be introduced at the beginning and she wouldn't need to be too pivotal, but she could show up in the mountains, acting callous towards the Gorons and claiming that the earth cog is the secret to creating good potions. She wouldn't be interested in the other cogs. She could then have a help/hinder relationship with Link as they both try to use each other to help get the cog, and she could even help Link defend the cog from the antagonist. However, at the end of the sequence, she would realize that all she really needs is self confidence, and she would make a potion to cure the Gorons. Then her part in the main story would end, the Goron's problem would be fixed, and Link could go on to the Shiekah/Gerudo theatre.