This... plus what are you wanting to do with it that you want it slim? I have had the Rhino Rack Pioneer platform and currently am running the Exposed Racks system.
Would you trust this setup to carry two basic kayaks ??Exposed Racks has a low profile rack that is probably little lower profile than the Maximus-3. I have had the Maximu-3/Pioneer set up so I can speak from experience that it is very low profile, but not quite as low as the Exposed Racks. Though it really depends what you want to do. Though we seem to be more interested in this topic than the OP!