Cyclocross Tire Pressure
Yes you can reduce the pressure and it will remain safe (cyclocross isn't a high speed high turning force type of racing). 

Your biggest issue will be pinch flats and rim protection. 

Weather and ground conditions should drive your pressure choice as well. The muddier the track the more traction you'll need.

I'd look at 30-35 psi to start and try the track on that.