I think you already know this, but seven acres in the middle of nowhere--especially if it is basically in your backyard--isn't going to yield a whole lot of money with the ideas you have so far. Two towns 20 miles away with 5K folks aren't going to pay for the costs of the paintball idea; if you want that for your own enjoyment, then go ahead and do it. But if you are expecting to actually make some money after landscaping changes, paintball equipment, liability insurance and possible rezoning of your land and the increased taxes from that, you're only kidding yourself.
Getting $200/year after herbacides, insecticides and fertilizer for brome on seven acres sounds like a good deal especially since you aren't doing any of the work. A plot that small is usually too small for anyone to waste their time any more.
If you want to put in a little effort, you could start a small "sustainable farm" and make a killing with it. Real, organic food commands a premium these days. Check out these guys:
http://theurbanfarmingguys.com/
They are actually based in KC so it really shouldn't be too hard to go and see what they are doing in person. If the stuff they do works in the inner city, it certainly can be done in the boonies.