Is there any particular reason you are calving in fall?
My line of thinking is this.
As a general rule in my area, the fall is dryer than the spring. And our winters are mild, since the gulf keeps our temperature somewhat warmer than places just 50 miles away from us. I will already be feeding a supplement in the winter, and I have a source for 17% protein, 5% fat feed at $9.50 cwt, so I don't mind feeding some extra in the winter to wet cows. I'd like to think that I can calve in October /November, then have spring and summer pasture for the calves, and sell as feeders in August...
Now there may be tons of holes in my plan, and I am certainly open to suggestion, but that's where I am at currently.