Infrared LED devices are quite easily defeated using an appropriate filter. Doing this though introduces another problem: most security cameras use an array of infrared LEDs for lighting. These are ideal because they produce almost no visible light to the human eye, so they're relatively covert. You can block the infrared LED emissions, but then you also block a very useful source of "invisible" lighting in otherwise challenging areas.

I think a much bigger problem with your technique though is... seriously who wears an infrared LED baseball cap? You would be very easily identifiable because that technique is likely to be nearly unique in your store; your attempt to mask your identity would have the opposite effect of drawing more attention to it.