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.
Ooops! Meant to say "aft of the USAF insignia".