I might be understanding this wrong, but when standing on one of the poles you should be able to move to any tile surrounding the pole in the same amount of steps. With your new solution you will only be able to move to the tile that is directly opposite of the tile you start from, or am I missing something? This would create strange situations where for instance Canada could reach northeastern Russia through the poles, but not northern Norway. But really, nations having trade routes, sending troops or even scouts through icy poles would be pretty silly in a world like ours, so you could just block them off like iv Civ.
However, if you want to simulate alien worlds with ice-free poles you would have to think of something. If I have understood you correctly or not I would in any case urge you to start adding some very basic gameplay soon. To create pawns moving across the world might get you to see benefits of certain approaches that you would not have otherwise, and might even force you to scrap solutions which seemed ideal without pawns. That would suck having to fix later. Just my 2 cents 