You need a real incentive, not a skin as a reward. Perhaps something along the line of character-class, but not one that is preselected at spawn. Using first aid as an example. Everyone "knows" basic First Aid. Bandaging ok, even tranfusing ok (but maybe with a 20% failure rate, and perhaps not back up 12000 pts. except over the course of a couple of days). Break a bone, a medic can splint it, but you walk/run slower and if not properly seen by a "doctor", you permanenty are slower/weaker/less stamina. Add eye injuries where you can't see as well, perhaps even limb injuries where you can only shoot with a single-hand. Find a medical book and after a few days of play you "learn" surgery where you can "fix" bad splints, field tranfusions, eye injuries etc.., . You you have to survive and so your team protects you and you help your team -- or perhaps become valuable to kidnappers(?). The concept can be extended to gunsmiths (yeah, your gun starts jamming after putting 5000 rounds through it), or engine repair. The idea is to recreate the reasons why people work together above and beyond sheer numbers with PvP combat.