the 5 acre minimum is not for the chickens, its for the neighbors, and its a legacy of zoning. Most likely the townuship had a buffer zone of "country estate", Res/Ag, or similar mixed use properties between true farms and typical suburban residential, which itself buffered more densely packed residential, subdivision, and similar use properties.
5 acres isnt even 500' square, its closer to 475, meaning the next residence likely isn't more than 400 feet away. Zoning usually has a number of setbacks from your own residence for ancilliary structures, meaning your coop will likely be closer to yoru neighbors even than that 400' bbuffer.
I live on 30 acres, I can absolutely guarantee that being 400 foot away doesn't make a rooster significantly quieter.
Given those factors, I would recommend bringing them up with the planning board directly - confront them head on - and help them draft zoning intended to mitigate two factors.
1) Noise
2) Odor
It doesn't matter that odor isn't a concern more than a few feet from a properly funtioning coop, people THINK that it is, including the non poultry owning board members.
So you want to talk about sight/sound barriers (either physical structures like walls or solid fences between the coop and the neighbors or "green" barriers like shrubbery, planted fences, etc) depending on what fits best with the character of the community. You might also concede ot a "no rooster" policy, as many do.
Re: odor, you want to talk about minimum areas/maximum number of birds and setbacks from your property line (don't fall for setbacks from neighbor's structures, that's not something you can control). You may need to concede inspection by county health/animal control of your facilites (chances are, its already in your code, so you aren't actually giving anything up, and restrictions on compost operations) after initial construction and perhaps annually thereafter. Chances are, they don't have the resources to actually do it, so again, you aren't conceding much (and make sure you have at least a 72 hour notice written in!). DO NOT concede to micromanagement my daily litter scooping and seperate barrels - that may be something you are willing to do, but it invites neighbors to complain that you aren't. Also, a properly functioning deep litter system generates less odor, less waste, and superior byproducts. Closed (barrel) compacting works well if you are a "scooper".
Those are my initial thoughts, anyways.
