To find gold in a cave, it would help to know if the gold signal you pick up is actually in a cave. Septic tanks for dowsing are like an underground vault, but with no gold signal. It is good to recognize signals from underground voids and structure to identify a gold cave. You would check for gold also, 2 very different types of signal.
I mentioned practicing over a septic tank, but your baited gold technique would need to be refined also. The gold search might be a good way to find the cave, but there should be response when checking for a cave at the spot.