I am not sure why bending the tow arm up would help the board plane better? If the problem is the heavier junk lines pulls the rear down and the front up reducing planing drag then it would seem to me you would want to do move the front tow location down and forward to keep the nose in the water? I use otter boards and prior to buying the 1/2 keel, Big Jon told me if I move the tow line down lower on the board edge it would pull harder. I am not about to run out and buy some inlines to prove my point but it seems a little counterintuitive.