The biggest load on the SA will likely be from the chain pull, luckily that’s usually mostly a compressing force on the SA.
The vertical loading of the SA depends on where you place the shocks.

As you see here, the closer the mounts on the SA are to the frame, the more of a load is placed on the arm itself. If they are in line with the rear axle, there is virtually no load on the SA in that plane. (As long as the are parallel with the direction of travel)
The other loads to worry about are the twisting and sideways bending loads. Both of these are strongly helped by triangulation of the SA either above or below, or both.
One more thing when considering where you mount the rear shocks.

Ideally i suppose you would want to be somewhat in the progressive angles, and defined want to avoid the regressive angles.
