Perhaps i can suggest that the % option is the least favourable. Try working in slabs, tatts tickets, or an offer of hour or two of help. After dealing with many farmers and businesses in the scrap metal trade a % option can sometimes be unviable, and I'm sure its the same with gold. the unknown question is how much will come out of the ground? Declaring the tally can sometimes be misleading for e either party. On a gold claim this may need proper negotiation, but in an everyday id try very hard to keep on the right side of the landowner, chances are they have been asked before (and there's always someone trying to sneak on). One landowner i know has dumped thousands of pellets of lead in his holes because prospectors just kept detecting them, so anyone friendly enough to come see him gets pointed in a different direction and will swap access for a quick chat. Perhaps asking the landholder what they considered fair rather than trying to make an offer might be the quickest way home, often its not what we ask but how we so that makes the difference.