I'm sorry, I misunterstood your first question.
Now, having understood its right meaning, I agree with the dimensions you suggest for the pad. Good engineering practice says that the pad should not be thicker than the plate it's welded to.
It can be thinner, of course, and the thickness should be calculated.
Now, for small pads as yours, it's easier to adopt a pad of the same pipe thickenss and avoid making calculations.
Giovanni S. Crisi