Hi Aidan,
I know this is of no help but I was just last week looking at a Rav 4 and the customer complained of this knocking problem.
I road tested it (long test run) and could only get the fault a couple of times, the noise seemed more on the right and a bit like the spring top mount bearing.
I checked all suspension and steering joints, no faults found, told customer that it needs to get worse for me to find it (really annoying)