What is your frame? It is the seat tube of the frame that suffers from too short a post. (Though many posts have material removed from the inside at the end so if you raise one of those posts too high, the most critical point on the seatpost, where it leaves the frame, will now have less material.)

With lighter steel frames and insufficient seatpost insertion, hard bumps can lead to bulging the seat tube at the end of the post. I would not expect a CF frame to fare any better. If I were you, I'd wait until I found a longer post. (Or if you really like the frame and want the great Thompson clamp assembly, have a custom post made. Thompson sells the clamp parts. I have two custom TiCycles seatposts with Thompson clamps (to get 60mm setback, far more than any stock post).

Ben