Hi Road: There are some questions I would ask myself in this hypothetical Cache,
1. Do you know who hid the Cache?
2. was it one of the property owners relatives?
3. Where did the hypothetical cache come from?
4. Would this person that Cached it want you to have this hypothetical Cache? This question may be impossible to answer of course!!
5. Was the hypothetical Cache hidden by your Relative? If So I would go for it Tonight!!!, It was one of your relatives money right!! your money now!! Grandpaw hid it gave you the directions to find it!!!!

,,Prove otherwise?
6. Does the property owner even know the Cache exists?
Even the goverment describes treasure trove Cache as money,bullion, jewells which were hidden for (recovery at a later date.) Sometimes the person that Caches money can't return to recover,If the Cache is natural Ore in a mine,,that is a different issue all together,But if it was hidden for recovery at a later date,Id say someone needs to recover it,,,If you are lucky enough to know where this hypothetical Cache is & it has nothing to do with the current Property Owner,Why is it wrong for you to be the recovery Person,,other than trespass, Someone hid the Cache to be recovered later,,they were on the Preperty to do this,,,,I wouldn't think a person would go to jail long for that!!,if at all,,it would not be like taking thier car,or 4-wheeler, I would say Do whatever you think is right!
It's Nice of you to be willing to Share 50/50 after spending your time researching the hypothetical Cache!!
IF the Property owner knows about the hypothetical Cache & is wanting to try & recover it thierself,, I would stay away from it!!