nsmikle -bang on the money-copy whatever you can find anywhere and you should be ok...
as for the 4 string arangement they obviously can measure tension only in the 4 strings and have to work out which is which...Bending ,twisting,shifting ...holy crap I ´d prefer not to have to deal with the maths to sort that out...especially when you can see on the REDBull picture the strings have no tension at all on one side..
I would have done that very different: build a support above the wing (whole width) and put string potis or maybe even rideheight sensors to it measuring the distance to the wing profile.
Or why not measure just the rideheight to ground at the leading and trailing edge of the wing? with one reference sensor in the middle you´d get all info you need.
the Rearwingendplate treatment is really an old hat. toyota had those in 2009 already.