yella, maybe you should pop up with a quick headbutt in clinching range before you attempt the takedown.
Yes smaller guys are disadvantaged in the clinch (I'm in the middle, so I've been on both ends of the spectrum), but then again, it's hard for smaller guys to take bigger guys down no matter what technique you're using. The key is the set up. Make them think clinch then duck under take the back and drop them face first. Of course it's all just talk and theory comin' from me, cause I don't get to practice takedowns enough.