The first rule is never allow police officers to search your trunk. A simple traffic violation does not authorize police to search your vehicle. The key here is that the officer is asking, though it may sound like an order asked in a nice way. If you open your trunk, you have given the officer permission to search your trunk. If you refuse permission, the officer may employ intimidation tactics but hold your ground, you have the law on your side in this situation, not the officer.
Most police officers support Second Amendment rights.
However, they also are obligated to enforce the law regardless of whether they think it's right or not. We don't ask police officers to arbitrarily enforce the law based on their personal preferences so don't expect an NRA member, pro-gun police officer to cut you some slack because you have an NRA sticker on your car. It would be nice if they did, but most won't risk their career for a citizen's Second Amendment right despite an oath to uphold the Constitution. If lawmakers won't support our rights, there's certainly no incentive for a police officer to make a stand and lose his or her job. The second rule is never carry a loaded firearm anywhere in your car in California.