I've thought on this issue many times and since entrance more often depends on a relationship of some sorts already having been established, I guess you'd be able to establish a meaningful agreement on a split depending on whether the people "like" you or not. But I have had discussion with one person who said they wouldn't let anyone onto their land again because when they did the guy came back over and over again, [they expected he'd found something] but they hadn't even seen him again. So to my mind, given I used to deal lots with contracts as a realestate agent, I reckon if you went in with a written agreement with spaces to put in name and date, agreed amount on finding something over, say, 5ozs, then it would give much more credence to it all. The landowner would feel they had at least some coverage, if something was found. Seems to me, to get into some of those places you really think there is good gold, then something has to be done.
Just a thought. What do you think.
Any contract requires names, addresses, date, period of access, agreed cut, signatures, witnesses, and a copy for each party.