I agree completely. But if you elaborate further on where you would obtain those items, I would point out the trail of evidence you would leave behind. Granted that evidence (e.g. your purchase of the stamper in a back alley in Honolulu) might not surface for years.
The point is... it can be done. An insider in the Hawaii state government could probably have pulled it off without much of a trace. For others, it would be more difficult.
I'd even agree that it's possible to forge the long form... but it's infinitely more difficult, especially if it is to survive professional examination.
But the short COLB is easy enough to forge that ANY variety of it is inadequate given the weight of the situation. Only the original long form (like the one McCain produced some time ago) is sufficient.