i have never done anything close to that sort of rust repair but my way of thinking would be to attack one portion at at time to keep the structure all together and not run into getting it all twisted up or mis -aligned. like a complete floor pan. then the trunk floor then moved to quarter panels and wheel houses. one thing at a time. forgive my ignorance if im off base here. you must know what your doing here to go this far down. id like to hear your plan of attack in detail.