The SR-71 was a seriously class act.....
Not so sure about that. Have you read 'Sled Driver'? SR71 had to enter a dive to go supersonic (to overcome transonic drag), had to have one engine in 'burner when tanking, and suffered serious 'engine unstart' consequences that led to the loss of a sizeable proportion of the fleet, and to the deaths of many crews.
I consider it more a 'cobbled together by Kelly Johnson in a rush' solution to a pressing military requirement.
It did the job, but was not a 'carefree' aeroplane, as evidenced by its abysmal accident record.