On my RV6 I went from "basic six" instruments to 10" Skyview by working carefully with Saber saw, tin snips, Dremel and files.
I do not remember any special structural issues. Mine was a complete changeover of avionics and instruments but I retained basic electrical system switches, etc. So I made up an overlay of the original panel. A prime objective was making everything accessible so big sections are easily removable for maintenance and future changes.
The Skyview itself does not require any depth. The main issues came up with finding accessible places for the extra boxes like EMS, Back-up Battery, network hub, and in my case, the Dynon Com and Airinc boxes.
(post #16 on the following page)
http://www.vansairforce.com/communit...t=23846&page=2