Given Ponga is going to play his usual role in attack, being a half, and refuses to move to the halves and wants fullback, we are already in this frankentein thing.
If we were able to get Ponga playing fullback role only we would be limiting him. He needs the ball in his hands and be creating. We need him with the ball in his hands and creating. Not as the only player creating anything, but he is a key factor in our attack.
He should be playing from 5/8, and linking up with Clifford both sides of the field, and putting on whatever plays he likes. We should have a fullback sniffing around the ruck and following ponga/Cliff in support to put the finishing touches on the space they create.
As it has been, there is nobody taking over that support player role a fullback delivers. Drinkwater could be that player, hell Mann could even be that player tbh. But we need that player.