Millet can grow pretty tall. What are you growing it in?
What you think caused the failed plot in the summer?
MY plot of crimson clover didn't do well in parts of my little plot this summer. MY problem is compaction in heavier clay loam. One section where most of the existing clover died from being underater for about a week. I dragged some spring harrows around a few passes to get a seed bed. That spot is doing great. A second spot in my home plot is an expansion of the plot. I got 3 dump truck loads of wood chips last fall. I put about a 1.5 to 2 inch layer of them over what was lawn. That spot is spotty, but doing ok. The last section I just srpead the crimson clover and rolled it into the soil with a lawn roller. That spot is about 95% red aramath, my main weed problem. I was worried 2,4D would harm some young apple and white cedar trees on the edge of the plot, so only sprayed with gly. I read that farmers in washington actualy spray 2,4D between their apple tree rows to kill weeds. I''m guessing they use a spray hood so the 2,4D doesn't get on the leaves.
Rainfall I do not think was an issue with my plot this summer. I am learning not every spot can do a good throw n mow method.
Trying to get some height this deep into summer might be challenging. I suggest whatever you pick, you may want to fertilize the plot 2 or 3 weeks after it comes out. Trying to put nitrgoen fertilizer in while you plant might harm the seedlings.
There was interesting thread over the winter about someone growing Ethiopian cabbage. There was another one about drought tolerant foodplot mixes for the southern states.
Planting some wheat into some millet with some peas clover and brassicas could be a nice mix. Perhaps mix the taller stuff more towards the plot edges.
My plot at home is my backyard. However I have a deer staging area. Behind my house is another house with 80 acres. They leave a dozen acres unmowed as a privacy buffer between me and him. I have 2 hiding holes where its a little 12x12 cave inside the brush. They get a little spooked they dart into the the travel lane, then pop right back out. I try to leave my food plots at camp brushy on the edges. While it is nice to have open forest right next to your food plot, I do think it makes them more nocturnal in their visits. IF they have a quick and easy way to hide, they use it during the daylight more. I have "Wasted" fertilizer many time on growing brushy edges, just toss it in there. I also cut tops of trees off. One plot at camp is next to the road. I take birch and maple trees and cut off anything growing past 12 feet tall or so. Not ideal for brushy edges, but it shades it up quicker. A nice tall treestand overlooking the brushy edge and seeing both food plot and more open forest is a nice place to be. I'm on mostly brich trees at camp by my 2 or 3 spots. Most of my treestands are only 8ft tall. With the tree canopy the way it is, I wouldn't get a good look into the forested spots.