Look into Land Shark. I'm 5'11", 270 pounds, and after testing a few bikes such as Cannondale, Specialized and Seven and finding they were made for sticks rather than stones I spoke with John Slawta (owner of LS) after having a sit down with Mike from Bicycle Station in Brooklyn. We took a whole bunch of measurements and my bike a cyclocross was made. it has a steel body with over sized tubing and the only major carbon is on the fork and handlebars. It's also light and seems to be supporting my weight with no problem at all. Give it a shot.
P.S. I also have a Co-Motion Mazama which is also a great Clydesdale bike.