Something like this
http://www.oceanbrake.com/stainlesssteelat.html
Given the load that a JSD can put on a boat, yes it is a bit more complicated. The 'Rule of Thumb' seems to be, each plate needs to be able to hold 1/2 the fully loaded displacement of the boat.
Or in other words, you should be able to, in theory, hang the boat off a crane by the JSD bridle....
I'll certainly consult an engineer, but there are some definite complexities around shock load, static load, and angle of the pull. (it isn't straight with an 'A' Bridle !')
My main concern, is where to attach to the boat really. Sizing the attachment gear IS a well known engineering activity (Shackles, lines, bolts, splices etc).
Stresses and strains on the boat on the other hand. Not a clue.
Unfortunately, this is one thing that is very hard to test, and frankly, you never actually want to if you can avoid it. The downside is if you do need to, your life may depend on having gotten it right !. Ripping part of the back of the boat off in a storm / following sea would be BAD (tm) !
Regards