The farther back you get them, the better off you will be. When you need these straps will be at times when you prefer to be very far aft. Just don't get your foot where it will interfere with the tiller.
I am going to try to verbally explain how I did mine, then I'll see if I can find a picture. But first I must say that a lot of people have used windsurfing straps and love them. Many of them are even adjustable for size.
I used a length of 2" tubular webbing (found in a mountain climbing store). I fastened it on the corner of the deck to gunwhale and this allows my foot to be on either the gunwhale, corner, or even deck if I wish. I doubled the end over on each end and fastened it with nut and bolt, one through deck, one through gunwhale on each end.
I provided backing in the form of a 1" carbon tube, split lengthwise. The convex side of the half circular piece is against the corner of the gunwhale to deck interface. I used ny-lock stainless steel nuts and had to use needle nose pliers to hold them because my carbon tube would not allow the clearance needed for a socket wrench. So aluminum flat metal may be better, would allow use of a wrench. Stay away from 90ยบ angle metal because the sharp corner would interfere with the radius of the corner joint. Also, the bolts need to be staggered so that they do not align vertically or else the two bolts will collide.
I sized the straps and determined the mounting points by forming them over my boot which I had stuffed with a rag to resemble my foot size.
These straps are so strong that I can lift the boat with them.
