Durability of Seat and Chain Stays on steel frame touring bike
Situations when the weight of whole bike + cargo (+ maybe a rider?) is concentrated on a small patch of kickstand's clamp and when a small dynamo clamps the same seatstay are really incomparable. In the first case it's a thousand Newtons of stress applied to a piece that was not supposed to be pressed in that direction, and for dynamo it's about five Newtons and the clamping force.

I would say just clamp your dynamo mount with a reasonable torque, or, if you are really paranoid, use a torque-measuring wrench and clamp according to manufacturer specifications. If it turns out to be loose at some point, simply re-tighten it.

Steel and aluminum alloy frames could sustain quite a lot of abuse of excessive clamping torque (but there is no need for it in the first place). If you make a mistake and instead of 4 N×m would crank it up to 20 N×m, it will still be OK. But I doubt that you will be able to achieve such huge torque with a typical size 3-6 mm allen key that is most likely used for the operation.

If your frame is carbon fiber, then a more accurate approach is recommended, as this material is more sensitive to clamping. However, I am not sure that there are many touring carbon bikes around.