Remove the military rank altogether. Make the rank locked permits attainable via missions to complete. Alliance now has two ships (kinda) in the type-10 and chieftain, those aren't rank locked but can only be purchased in alliance space or at Jameson Memorial. I mean, you already need a god awful amount of money to buy and outfit the cutter or corvette. I know there will be Cmdrs that bemoan this idea (generally the ones that have slogged through the horrible grind, I myself hate it, but dat cutter tho) but it generally prevent anything like this "too much rank" missions from ever occurring again