I know this is an old post but I personally have replaced a frame and can say it really isn't bad or all that intrusive of a job. Basically disconnect the engine stuff like you are going to pull it, unblot the master cyl, disconnect the sterring shaft and an oil cooler in front, an evap line by the frt left tire, body cables and ground wires and the fuel filler bolts. The body really stays intact except for pulling back the carpet to access body bolts. The worst part was disassembling the front susp on a bare frame (no weight) and laying all of the hard lines the way they came off.
I did 1 frame but many body separations for engine repair. I wouldn't hesitate doing mine this way at all