Before I break something: any tips on body to rear axle brake line connector removal?

You may be able to salvage the hard line. The hard line flare nut does not need to be loosened from the tube.. I put honkin vice-grips on the flarenut, and while it's in the body clip, WITH a wrench on it, use the vice-grips to " crack " free the connection. Then remove the clip, just pull the line free of tab, far enuff to unscrew the hose, screw on new hose, install in tab, secure with clip, support hose/tab with wrench, then tighten the last "cinch" with the seized nut on tube. Done it often on an otherwise perfectly serviceable tube.