Don't forget, if you put 3, 8 frame supers on, you will have 2 sets of 2 boards on the supers that will be sitting over 1 and 1/2 frames each.
The 2 sideboards boards on the middle super and the 1 board on the inside of each of your two outside supers. Each super being a full (4) sided box.
Sit 3 eight frame supers side by side touching one another.
At any rate I'm going to make me one. See how it works.
doak