I don't think this is right. Measuring a photons position to the plank length or below (probably not possible) would just mean the photon has a very large uncer

I don't think this is right. Measuring a photons position to the plank length or below (probably not possible) would just mean the photon has a very large uncertainty in momentum. But that's no different than saying if you take a single slice of a 44.1khz PWM data stream you'd have 100% certainty of amplitude and 100% uncertainty of frequency.