From the rules it seems to me like there will be an impasse in this game, when both Kings reach the enemy camp. In the sense that the game becomes unwinnable because the players will surround their Kings with an impenetrable fortress of promoted Pawn protecting each other multiple times. You just dropped the rule for handling this situation satisfactorily. I doubt that this is a good thing.
From the rules it seems to me like there will be an impasse in this game, when both Kings reach the enemy camp. In the sense that the game becomes unwinnable because the players will surround their Kings with an impenetrable fortress of promoted Pawn protecting each other multiple times. You just dropped the rule for handling this situation satisfactorily. I doubt that this is a good thing.