Note the built-in JATO units just forward of the USAF insignia on the fuselage. Incidentally, this is a B-47A, so the incorporation of JATO must have been part of the basic design criteria for the B-47 Stratojet. I think that they wouldn't integrated JATO into the basic airframe if it was as much of a problem as you said it was. Probably had more to do with the relative lack of thrust that you could develop on the early turbojets.