David, it gets more fascinating by the day...and I look forward to the W/E Oz !
If on yr next expedition, and Lidar is unaffordable, what about the hand held magnetometer, as I mentioned in an earlier post.
In my bush bashing mineral exploration days in the Iron Range rainforest, and other bush terrain, we would cut a Master grid line across the area of interest ( lots of machete swinging!) say N -S and then cut lines E-W at intervals along this line.
Readings taken over this grid, stepped out every 10 paces or so, could the plot the anomaly,... mag, geiger counter whatever the gadget.
You say yr specific area of interest is whittled down to ..fairly small ? Lots of strong arm local folk should get you a grid cut over within a reasonable time ?
Hopefully some big bucks might come and then you can really do the business..!!
best regards