The clover is going to live many years if everything goes as planed. The oats will only last till June. It is still to early for corn in your area I would think. Trees should be leafing out before you plant corn. You wont gain nothing planting to early. The deer wont need/use the corn until fall, which is something I think will work good for you. The shot plot will most likely be done by late June also. If you plant the Brassicas in late summer/fall it will last most of the winter. I had kale live all winter this year and it got down to -4. Kale is one of the seeds in shot plot.