I would be willing to bet that the corn will produce an ear, take it the deer won't eat it to the ground before it gets a chance. The problem you would run into is that the ear wouldn't be "fully" produced before the first frost, damaging the grain, and it will more than likely turn black (the grain). This is due to the kernals are still full of sugar, and hasn't gone into "hardening" or drying down.
Beans will probably do fine right now. You will have frost kill on the top part of the bean, and with the late planting you are greatly reducing your yield of beans, but heck, YOUR FEEDING IT TO DEER.
Oat will definitly be great for the deer.
I say go for it man. I think you will have a nice food plot that will feed the critters later in the year.