If you REALLY REALLY wanted to, you could un-fuse the Fusion, partition it, partition the HDD, re-fuse part of the SSD with part of the Fusion, bootcamp the other partition of the SSD, and use the other part of the HDD for extra Windows data. However, this is all a royal pain in the hiney. Personally I just accept the fact that Windows doesn't run at SSD speeds, and I go into bootcamp no more than once a week probably anyway.
Also bear in mind that many games do have OS X versions that perform well.. you don't need to game exclusively in Windows if you don't want to.