Since your pond has recently been dredged I would not be concerned about winter aeration. Remember no such thing as safe ice with or without aeration.Consider keeping snow off of at least 10-20% of the ice if snow covered for more than a month. Remove in strips if possible.Moving one of the diffusers into shallow water may still overcirculate your size pond.I will have all of our ponds that we maintain shut down in the next two weeks. The ones recently checked are 90-95% saturation and from 47-52F,with 8-10 ppm DO Yours is likely in the same range.Once your average dailey temp is in the 40F range for a week or so just shut it off.At that point your no longer aerating just circulating.PS All of the above posts provide you with great information.