If the Outpost bunker shelter is tied to killing the Punisher, the encounter should not be a random spawn.
I love this game. Build 2 ramped up the AI skill and the game is genuinely harder, and by extension, more fun. The Outpost bunker shelter is powerful, both for its proximity to the Gunsmith and Vostok. Locking this behind a random encounter that requires you to sprint to a road/crossroad, engage the vehicle, hope it stops, then kill the slightly harder boss mob all while not getting killed by regular spawns and the boss and his adds, feels rickety. Too much luck is involved. The Punisher encounter should require preparation, a great loadout, strategy, and skill. Hell, he should have his own little map. Make it tough to get to. Make it even tougher to complete and escape. It should not be a random event, which becomes less likely as other events are unlocked. It should feel like an achievement, not luck.