the limiting speed factor of the SR-71 was the wing leading edge temperature of 734 degrees
As with any aircraft the 71 was subject to any number of limitations, but airframe temperature was not one of them. The crew had no info on skin temp in any event. However compressor inlet temperature was the major limiting item (427°C).
Thread on the Concorde inlets here
http://www.pprune.org/tech-log/42690...ke-thrust.html