I wouldnt bother upgrading to triple screen just for CLOD. It doest work well enough to justify it even with my madly modded and overclocked system running 4way SLI. I have to lower settings to get it smooth and above 25FPS at 6048x1080 with 3x24" monitors. Its stilll very playable but its not as smooth or detailed as a single screen.
Lots of other games work well with 3 screens though including the old IL2 1946.
Here's an old video I made with a very early version of CLOD. The latest retail patch runs better but its not consistently smooth enough to justify running 3 screens. If you do go down the 3 screen path for CLOD you will need 3GB vram video cards as a minimum as it uses 2.5GB Vram at 6048x1080.