I did something similar recently with fairly good success. Dump the flakes right in without milling. I also added a sizable amount of rice hulls to aid in runoff, I highly recommend it!
With 20-25% corn I think you'll have enough enzymatic power in the mash. Depending on how "lite" you want your beer to be, you may want to consider adding extra enzymes. In my case I added Convertase (alphaglucosidase) to produce a low-carb beer and attenuation was off the charts. If you decide to add enzymes just know that you won't be able to repitch that yeast crop unless it's into another "lite" beer.
Head Beer Guy