You want planar mast mounted as high as you can thus the "otter boats" will be out to the sides and tow line will be high with releases sliding down it.
My Big Jon mast is mounted on my bow, so I have to reach up with outstretched arm to grap tow line an pull it down to hook on the release rod line. Take a look at Big Jon web site they have a picture of best mounting locations. One other thing... it takes a while to get used to fishing with "otter boats" but once you get the hang of it they are awesome !!!