I do not think in game donation rank is necessary on the forums, it does not mean anything. If any rank was to be put up on forums it should be a separate rank depending on how active you are on the forums.
To give a good example let's say a player has been playing for a year and only super donator but knows his way around the forums and is very helpful. Then you got someone who just started playing a month ago and is vip. People will take the vip players opinion over a super donator opinion no matter who they are.