After going through the archives it seems that the recommendations for twin fin trailing edges is between 10" and 7.5" from the tail. But it also seems that board length and width are a consideration…fins moved forward for narrower tails and moved back for wider. I was wondering what the rational is for this. Also, is there any consideration for where the back foot is placed in regards to the fins? And, does adding twinzer fins change the placement of the main fins? Thanks, Ken