I know it is possible directly with a 1m scope and an EMCCD based camera which has effectively zero read noise
https://www.cloudynights.com/topic/285383-crab-nebulass-pulsar-is-blinking-not-a-joke/?p=3632352
but it might be interesting to run the figures for a modern CMOS camera to see if given a reasonable size scope, summing enough images at each phase could pull the signal out
Robin