I have had good experience with crimson clover in south central PA doing well. Planting it in early to mid September, it sprouts out good, gives the deer some food to eat, adds lots of N to the soil. In the spring, it really takes off and the deer love it. Helps them recover from a tough winter. I then usually til it into the soil and plant my summer annual mix. I really like it for logging roads that get a fair amount of sunlight. It can handle acidity better and doesn't need all the lime other clovers may need to do well.
Crimson may or may not survive the winter, depending on where you are in PA. We have wintered some over here in Venango County, but I think it was not 100%. I love the stuff because it smells so good when you mow it...like small burnett. I have not tried it for a quick fall crop, but it is certainly cheap and germinates well. I wondered if it would get large enough to make a contribution...sounds like it can. If it overwinters, it will be the first clover to take off in the early spring...which is a key time of nutritional need for our deer.