[HayZee518]

Just an idea but think about this. Where you excavate the ground for the base, put down a smooth, level layer of sand. On top put a layer of 6 mil poly. On top of this put 2" urethane panels with the joints taped with duct tape. Pour your concrete on top of this, within forms all around the slab. Screed it off level with the boards and finish it off with a whirly-bird trowel (powered trowel) let it cure slowly - keep it moist. With the urethane you'll have an isolated slab above ground with insulation board underneath so it won't be so cold.