Yes, there is a system proposed by Frankite ( for sure one of the true fathers of modern foil design and build) on the french forum.
http://kitefoil.forumactif.org/t1580-me ... ion-du-mat
I just read it again and will get some more specifics before posting here.
In a nutshell, as you mentioned, it is about fixing the base plate vertically and adding weight to the strut and measuring deflection.
And adding weight to the fuse and measuring twist.
I am off to sleep so will try to get to this tommorow.
It would be cool if guys out there with other foils (home made and commerical) could add their findings as well!