Yeah I love that plane too. Mine will be on display downtown for the whole week end, so I won't get to fly it...[]
I still have to try my new oleos out as well as my onboard video system...
About the scales, I have the same kind as yours, 5kg max, with 1g accuracy. I just think it would be easier to place them in areas you are sure of the symmetry of, like panel lines, wing tips, servo pockets...
You them would just have to carve small "beds" out of foam for the chosen areas, for the plane to rest nicely on.
You would not forget not to count the weight of the beds of course.
On my scale, when I turn it on, no matter what is on the plate, it initialises to 0.
So I'll turn them on with the beds on, then I'll add the plane...