I just replaced the panel on my RV4. I bought a new blank from Vans ($55), and cut it out with my jig saw (20 minutes), using my old panel as a template. It fit perfectly. Then I marked my new equipment and cut those holes out with my jig saw - maybe 2 hours with the saw and a vixen file. These holes would also have to be made if you made individual panels as you suggest. I mounted nutplates for attaching the EFIS screens and radio rack, and I was done - aside from painting it. All in all, it doesn?t take that long, and is easy to do.
RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
RV4/bought 2019 Flying
RV6/Used kit purchased 2021 building