[Larryjk]

ksubuck, You are fortunate to be in farm country. Most of those folks are probably shooters also. You might want to contact them about your plans and see what their attitude is! Most of them won't care unless they hear whining bullets. Ours is a municipal range, out of town, shooting away from town, berms about 20 feet high at the impact area and 14 feet along the sides. Some folks mentioned an over head baffle so you couldn't shoot over the backstop.
We finally had a ($) consultant from Florida come in to evaluate our range plan and apply some common sense to the local situation. He didn't feel the overhead baffles were necessary because there weren't any habitations for over ten miles. You can spend a lot of money, but some lawyer will say it wasn't enough.
The main issue is never having a bullet go where it shouldn't be.
Check to see if county regulations have any issues. If it is your personal range , it is easier. If you invite people in, you are dealing with the unknown. The box type backstop you describe should contain the bullets (lead) and have a lead remediation plan if the county requires a plan. The plan can say you are going to keep the lead in the box until you abandon the range, then the soil will be buried in an approved landfill. If you have a plan, they can't shut you down for not having a plan.
Good luck.