I looked at some FRP fenders the other day, couldn't have been much more than a couple of kilos each, much lighter than the standard ones!
But before you start spending money, strip everything you don't need out and see how it feels.
Then start to replace stuff with lighter replacements.
Also in regards to the weight of carbon and glass, a propperly designed and layed up carbon part will be lighter than a glass one everytime. If carbon bonets are weighing the same as glass ones then something is seriously wrong and you are just paying for the wank factor of it being carbon...