From EN 14766:2005: Mountain Bicycles - Safety requirements and test methods, published by the European Committee for Standardization. Reference courtesy Marcus Schroeder (of EFBe, a bicycle testing firm in Germany) via LinkedIn.
The tests described here are roughly what my Topper would need to pass. (I've excerpted here for clarity.)
Note that 4.14.4 applies only to the saddle itself, so the current design wouldn't need to go through that step... but I've got schemes which might change that.
4.14.4 Saddle/seat pillar - security test
188.8.131.52.2 Test Method
With the saddle and seat-pillar correctly assembled to the bicycle frame, and the clamps tightened to the torque recommended by the bicycle manufacturer, apply a force of 650N vertically downwards at a point 25mm from either the front or the rear of the saddle, whichever produces the greater torque on the saddle-clamp. Remove this force and apply a lateral force of 250N horizontally at a point 25mm from either the front or rear of the saddle, whichever produces the greater torque on the clamp (see Figure 48).
4.14.5 Saddle - static strength test
184.108.40.206 Test method
With the saddle clamped to a suitable fixture representation of a seat-pillar and the clamps tightened to the torque recommended by the bicycle manufacturer, apply forces of 400N in turn under the rear and nose of the saddle cover, as shown in Figure 49, ensuring that the force is not applied to any part of the chassis of the saddle.
4.14.6 Saddle and seat-pillar clamp - fatigue test
220.127.116.11 Test method
Insert the seat-pillar to its minimum insertion depth in a rigid mount representative of that on the bicycle and with its axis at 73* to the horizontal. Mount the saddle on the seat-pillar, adjust the saddle to have its upper surface in a horizontal plane and to be at its maximum rearward position in the clamp, and tighten the clamp to the torque recommended by the bicycle manufacturer. Apply a repeated, vertically-downward force of 1000N for 200,000 cycles, in the position shown in Figure 50 by means of a suitable pad to prevent localised damage of the saddle cover.
The test frequency shall not exceed 4Hz.