Your best bet by far is to do a "test fit" of the rails prior to deck mounting.  Put the primary occupant in each cockpit and move around the rails to find the most comfortable position.  Wearing your prefered paddling shoes is a good idea.  Placing the rails for my wife's Ch16LT below:

Mark N

I appreciate your suggestion so for logistical reasons, I attempted a sort of mock-up.  Turns out my side panels are so shallow and the deck so minimal in the mid-cockpit area that the brace assemblies are unusable.  Anyone want two pair, mint, usused condition?  Live and learn, perhaps...