Howdy. Best to read the message "Gammons and Doubling Cube - Now possible" first.
The gammon idea's fine but I've just tried to do the doubling cube thing and discovered the fatal flaw. The doubler gets to see their dice first. Lol, what an advantage; you could never accept a double!!
It could only work if each player sent their move by message, in advance, so the opponent could consider doubling kning the position but without knowing their dice. Then they'd have to send a message back ("Double" or "No dDouble") which the mover *must* wait for but only open after they've sent the move off. (This is so that the appearance of a message doesn't come to imply doubling). And this message thing has to be done by each player between each move.
Confused?? Try it, it's ...
... worse, lolol. *Nobody's* going to do all that! ;-)
.. back to the drawing board unless, maybe, you've got some better ideas ... ?