It would be hard to beat the great white cedar swamps of northern Maine. Besides providing super thermal cover and a great edge to still hunt when flanked by alders, white cedar is reported as being the only single plant that can sustain a deer through the very long northern Maine winters. If cedar grows in your area of Maine, creating a white cedar stand in and along one of your swamp areas would be an awesome accomplishment. It would take a huge effort and seedling trees would need to be fenced for sure to get it started. Whiter cedar swamps though have been a key ecosystem for winter deer yards since "forever" and likely are among the best winter deer yard areas anywhere. Keep us updated on whatever thermal cover you decide to plant.