First idea is based off of civil war reenactment I once did... We had 3 mountain guns, enough spring field rifles for each soldier, fortifications, etc... is was a great day.
for paintball keep the mountain guns and fortifications but replace the rifles with markers. maybe modify the cannons so they fire grapeshot paintball and "uniforms" (basically jackets and some kind of leg cover) that can be rented out. different scenarios can be acted out based on different battles. call the field "crossroads". the tag line would be "where the past and present meet."
Second idea would be (and this is if you have money) to go shopping for an old military base.http://www.missilebases.com/properties is a good place to start. clean it up then host paintball tournaments there. transport the players onsite via a vehicle from herehttp://armyjeeps.net/armor1.htm and just go at it. if people are willing to pay $50+ for a day at six flags then how much would they pay for a ride in a M75 TRACKED INFANTRY CARRIER to a combat zone in an abandoned military base. zombie day alone would be worth the price... (personally the missile silo has resident evil written all over it.) hell rent it out the real military for training exercises... Name:"The Proving Ground"
Third idea: Night woods ball in a haunted area. Best of both worlds, ghost hunting and paintball. Name: "Ghost Adventures" :p lol (keep in mind the waver has to mention that the owner is not responsible for anything that happens to people due to pissed off spirits.)