thoroughly agree with Lorraine’s suggestions especially JD for steering group – often what people think the job involves and what it will let them do is not actually the purpose of the role.
and your idea of zoning the neighbourhood area and have elected reps from each is also a good idea to ensure a wide input from all parts of your local community. however it will add to the cost and time of administering your governance. not a reason for not doing it but just one to plan for.
but finally what i really wanted to add was to say that where i live (waterloo central london) we are a community very much made up of both business and local residents, as well as a lot of charities both local community ones and national ones who are based there. as a result in order to have a truly representative steering group our constitution sets out a number of member constituencies for large businesses, small businesses, large charities, small charities, TRAs and local residents. each constituency votes independently to elect members of the steering group (with sufficient numbers for the local resident, TRA and small charities constituencies so that businesses and large charities cannot control the board. this way all are involved apprpriately and it has strengthened what we can do, and the buy-in from all in our community. maybe something to consider re. bringing in landowners and local businesses so that they have a real stake but dont control. rather than just having them on the board but no vote. you can see a copy of our constitution at http://www.sowneighbours.org/documents-archive/constitution-of-the-south-bank-waterloo-neighbourhood-forum/ to see how we have set out the membership rules and the voting for the steering group. again though do note that such a structure does increase the admin of an election.