Property taxes are different in certain parts of the State, so my information may not be accurate. Hopefully a local member will also provide information.
To the best of my knowledge, as long as you close by May 1, 2009 you should be able to file your homestead paperwork and be taxed at that rate. As previously suggested, tax boards allow the owner to request a review in March. If you close by then, and purchase at less than twice the SEV of the property they may accept your sale information. (however I wouldn't hold my breath)
Based upon public records, through Realist, the 2008 taxable value and asking price on Trulia are very close so there may actually be a decrease in value recommended for this property. I suggest speaking with your buyer's agent to see if they will run comparable sales, in accordance with those allowed by Battle Creek township (each have their own rules of sale dates they will accept) to see what is happening to the value of similar homes on the lake.
I'm not sure about your area, but if you are requesting much of a decrease in value you may expect a personal inspection of the property. If public records information is lower than actual information on the home, you may actually get an increase in value.