You should be fine
I rode a Trek OCLV for 4 years with no issues. I am 6'5", 250 lbs, and the biggest issue I had with the bike was it was only a 62cm (the biggest they made). I have since moved to a Seven custom, which fits more like a 65cm bike so is much better. I have the full carbon fork on the bike, with NO issues in the past two years. I have about 3cm of spacers on top of the headset, but my frame also has a 1cm headtube extension.
I never went the carbon seatpost route as I have been a Thomson rider for years. On the carbon frame a carbon post seemed overkill (especially since saving weight was, well, stupid at my size). Might be a nice upgrade on my Seven, but ride quality is still great with the Thomson so why change?
I also agree with the others that the one place to avoid carbon is on the wheels. At our size the superlight climbing wheels just don't make sense. I made the switch to handbuilts and love them, but I also rode plenty of factory wheels that were nice, fast, and great looking. I just stayed away from the stupid light, low spoke count wheels.
While I never rode them, I know there are a lot of Clydesdales who post on RBR that ride Look frames. You may want to do a search and check out why.