I have never heard of such a thing, an "emergency" tender. It used to be in MA that T/T was allowed if the motor was 2.5HP or less; no more. Anyway, it goes state y state, country by country.Marking the dinghy as "tender to" in order to avoid registration presupposes in the eyes of the law that it will only be used in case of emergency and if caught scooting around and there is no emergency then the result will be a fine.