This could boost PvP aswell. If you think about it, there would be a little amount of convoy's so players will want to be set up and ready for when the next convoy comes through players... it will be rare for one group of players to ambush the convoy as everyone is in need of supplies. Also have NPC soldiers have to get out and fight back, no zombie bullshit unless you start the ambush near a town or city. Or perhaps once all NPC's have been killed you can take a truck each and drive off to safety with the loot? Obviously the soldiers will have to be able to fight back and a reasonable force. This could set some stress on alot of players as they have to watch for snipers too. Another thing rocket could add along with this are supply drops in the airfield or in a field, little cover + fairly good loot = massacre.