dresdali, coan.net: The difficulty with a batleboats-style setup is that the frogs live on the same board and may not share a square. What should happen if both players choose the same square? Disallowing the second player's placement would give away the other's frog.
One way round this would be for each player to place, say, ten frogs and then the system would choose five of them randomly. The ones not chosen may or may not have had a clash but there's nothing to say. The disadvantage is that the random choice removes part of the player's choice, in the case where they wanted to put their frogs in a particular configuration.
Another, and easier, option is for a player simply to be able to regenerate the random placement until they're happy with it.