Namtrak,
I second your thoughts. You are not suggesting a workaround at all. ;)
Putting plasterboard over a warped frame wall with damaged plaster and laths is asking for a less than good result. :o
The dirty bit is done in a weekend at the most and then as you sugesst just do what you need to do. Packing studs and noggins is easy with string lines set to where you want the finished surface to be. Much better than having a wavy wall and workarounds that are not the real thing. As a matter of interest modern lighting has a remarkable ability to show things like wavy walls up. :eek:
FWIW