SKS makes raceblades in a fat version that easily covers a 27 mm tire. They tend to vibrate and shift a bit more, so if you have any size tire at all, you want the fat raceblades just so you aren't always getting chafing or rubbing on any tire regardless of size. Raceblades are good for easy-on easy-off convenience. They rub marks on your frame where they clamp on unless you use a strip of clear 3M hood film to wrap the frame under where you mount the fenders. This stuff works well: http://www.amazon.com/Clear-Universal-G ... B003EP52BU
Raceblades take care of about 80% of the water, but after 40 kilometers you'll still get wet (and even more, dirty) from the ride. If you use full fenders with long flaps, you'll only get wet from passing trucks or from stuff falling from the sky. If you don't have fittings on the bike you can substitute with creative use of vinyl-covered stainless P-clamps. The first installation is a pain and can take an hour or two, but thereafter you can install or remove them in 10 minutes so you can remove them for the summer and not feel bad about it.
The ideal solution as pointed out above is to have a rain bike. Equip it for durability -- Ultegra instead of Dura Ace cassettes and chains, cables that are more water resistant, a larger saddle bag with more parts and tools, wider rims, bigger tires, etc. You'll be happy and won't have to feel so guilty if you don't clean it up every night.