I personally have always been under the understanding that here in Victoria it is pretty much the way it has just been described to you though as stated its up to the rangers interpretation and the word or words (portable) or (non mechanical) are also hard words to interpret, pretty much in a nut shell if the equipment cant be picked up and carried away by hand or on your back all in one go then its not really portable and you will come across rangers that will not except anything less of the word (portable) its not like you could rig a trommel and sluice /(highbanker) onto a trailer with a huge water pump and just pull up and start digging away and expect rangers not to get their knickers in a knot and on top of that I think there is a limit to the amount of material allowed to be processed each day also remembering that one must put the area back to the way you found it before one leaves including right down to the leaf litter anyway that's just my 2 cents worth and I hope it gives you a better understanding of what is expected from us as hobbyist. regards greencheeks77