You'd need to convert that field for the proper zoning which I doubt you will get if you build it as an airsoft only field. You'll have to probably go airsoft and paintball.
As well there are many problems posed by being so close to other buildings and such. I know there is a field in North Van which is bordered by a community centre on one side and a set of train tracks on the other. There are apparently a lot of problems with paint "accidentally" hitting the trains as well as the wall of the community centre on the other side. Note there is mesh but it doesn't protect against everything.
Chayce: although your post about the location wasn't thought out very well I have to commend you on the rest of your post because that's a pretty good observation of what a good playing field/level is although you'd still need to worry about redoing the field and changing it up or it will get boring.
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE