Right but the SR-71 had a pretty significant fuselage cross-section that is basically pure drag. If going for max efficiency, the entire nosecone of the rocket

Right but the SR-71 had a pretty significant fuselage cross-section that is basically pure drag. If going for max efficiency, the entire nosecone of the rocket should probably be the air intake. Basically take one of the SR-71's engines put it vertical and mount the payload inside of it under the shock cone. TWR needs to be high enough to eliminate the need for wings. Some of the newer missiles like the BrahMos are designed like this and have a ramjet powered second stage to save on oxidizer. It doesn't reach anywhere near orbital speed, but with this design, the shock cone takes the majority of the heating vs. the SR-71 where there were many exposed parts and materials.