I think nations will be anxious to get into the game too. At least the ones with a chance for getting there first, the rest will bitch and moan.
And ultimately nations must control land in space to bring governance there. The way to do this is by creating leases on space property. We have a lease at Guantanomo Bay that is open ended. It is ours to use until we abandon it. This is what must be done with space property in order to encourage space exploration and exploitation.

"Obviously, there will be no idiotic planting of a flag and claiming a whole planet "

Agreed. Although there must be some way of determining how much area could be claimed in a given landing, and if that area is determined to be say, 5 square kilometers for instance, that would mean most asteroids could be claimed by landing on them. And I also agree that there must be some productivity clause in space land claims.