Keeping a PIR on all the time
A PIR has a pyro-electric sensor, filter, and Fresnel lens that is designed to detect the IR from a human body, which has a wavelength of 5um to 10um. A IR LED usually emits in the region of 800nm to 900nm. So, a PIR will usually not detect the IR from a IR LED. You can easily prove this by aiming your TV remote at the PIR - it should not trigger it.