I ordered Lenco 9X12 standard mount Trim Tabs. Just got them and I think I made a mistake. The instructions say I need 15" to mount them. I have a 208 with swim step. and only have 12"! I will have to return them. It looks like I can only put 12X12 or 12X9 (EDGE MOUNT) the first number being the lenght out the second number being the width that is mounted to the transom. With the edge mount I will only need 11" to mount the acctuator. Any heLp? 12X12 or 12X9 or do I still have it wrong?