May the notice of race or sailing instructions state that, while the right of appeal is not denied, final regatta standings and awards will not be affected by any appeal decision?

No. Rule 86.1 prohibits changing any part of rule 70 or rule 71 in the sailing instructions. An appeal involves not only the adjudication of a dispute on the meaning of a rule but also, in the event of a change or reversal of the decision of the protest committee, an adjustment of the results of the race and the final standings of the regatta on which the awards are based. Rule 71.4 states that the decision of the national authority is final, and this decision must be implemented by those bodies subject to rule 85 and governed by the rules: the organizing authority, the race committee, the technical committee and the protest committee.