I know this thread is a little old, but if you are starting to look forward to cross season (as I am!), don't give up on singlespeed. A few quick things: Definitely up your gear ratio. I often use the same as winebelly: 38x16. Even 38x17 would be much better. But for a flat rolling course, I've even run a 38x15 and ended up finishing top 3. Gearing totally depends on the race and your comfort, but undergearing is a quick way to be in the back unless you can spin like a mad man. One good way to boost your rpms is to ride your singlespeed in the city during the week. It pretty much sucks because you are riding so slow (compared to anything with gears, or geared for the road), but I've noticed a huge boost to my cadence after riding my 38x16 cross bike on the road for 30-40 miles a week.
Part of the reason i love singlespeed cross, is because I can keep up with so many cat 3 geared racers. I love starting a minute behind them, and then catching a lot of them within the first lap. And the second lap. A little twisted, but it is quite fun. I hope you get to try singlespeed out again, and have a little bit more fun in the pack this year.