Getting spring planted beans through to late fall or early winter is a many tentacled beast. I have had both successes and failures through the years in this department.
Here are some thoughts based upon my experiences...
If you have higher deer populations, then you either need to bite the bullet and e-fence them off OR go with enough acres to outpace them. Generally speaking, you will need 2+ acres to have a chance of them not getting wiped out...but that varies on where the plot is in terms of visibility. But really, 4 or more acres would be more like it. A hidden plot = more pressure. A visible plot = less pressure. But there are of course downsides to visibility...such as poachers.
I finally succumbed this year and e-fenced about 1-1/2 acres of beans. To my pleasant surprise, the fence worked and the beans were never marauded during the summer. (Note - I think this was also due to there being plenty of other food available this summer. Had it been a dry summer, etc, then I suspect there could have been more motivation for the roaming herds to have defeated the fence.
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If you want a coop to spray them for you...and I am convinced that you WILL NEED to spray beans after emergence, then know that they do not want to diddle with small plots. They want to put those wings down on those big sprayers and go...so I have found that it will be hard to coordinate with a coop unless you have 4+ acres to spray and even then, that is small potatoes to them. We sprayed our own 1-1/2 acres with a ATV mounted sprayer.
If you can get beans through to late December, I don't think there is anything that will draw deer better at that time. But after about 5 or 6 years of trying to "poor man" a couple of acres through to the end of the year...I have only managed it once...about 5 years ago now. Drought, mistimed or missed sprayings, drought, too wet to plant on time, drought, too many deer, drought, etc, etc, etc,...oh and drought...have caused me to whiff several times.
Even so, I have generally not spent too much on these follies and the deer have had some good bean eating during the summer and I have salvaged most of those plots with a rye/mix planting in early fall. So not a total wipeout, but there are plenty of factors to battle to get your plot where you want it, when you want it.