Lets say you have an 8 ft average on your .5 acres or 1.3 million gallon.You move one diffuser to a depth of 4 ft and cut 50% of the total compressor flow (exhaust it off at the deep water valve at the manifold)2 cfm at 4 ft will still lift 1400 gpm or 2.016 million gallon per 24 hr day.If you try this move the station to an extreme end of corner and get it close to the shoreline.I would also consider putting an inexpensive timer inline to run perhaps dusk to dawn only. You can melt off 6 inch ice easily in 24 hours.Your water will be at 10 plus ppm DO soon and even though you have "plenty" of fish stocked their need for moderate to high levels of DO is getting to be less each day it continues to get colder.Dont be concerned about having to have open water in your situation for this year. If you had snow free ice when you get ready to leave for a month I wouldnt worry about it.