Generally, we mount all of our speed controllers (mostly Victors but some Jaguars) on perforated aluminum mounted in the frame. We generally use folded sheet metal chassis, so we would make the bottom of about half of it out of perforated aluminum and mount everything on that. The cRio should be mounted on lexan or wood to be electrically isolated, but nothing else needs to be isolated. I'll see if I can find pics of it on old robots...
http://jasonjmonroe.com/TWMM/photos/...d/P2149916.jpg - Buzz14 (2009) Jaguars in chassis sides, with PD board in middle.
http://jasonjmonroe.com/TWMM/photos/...d/P2149918.jpg - Better picture of how we fit the Jaguars in.
http://jasonjmonroe.com/TWMM/photos/...d/P2149898.jpg - Top view of chassis. The PD board is located to the right of the battery, slightly out of sight and hidden.
http://jasonjmonroe.com/TWMM/photos/...d/P2149900.jpg - cRio and DSC mounting, where they fit in the frame. the cRio is mounted on polycarb.
If we didn't have a ball manipulator system in the middle of this robot, we would've put a sheet of perforated aluminum in the middle area and put all of the Jaguars there.
A direct answer to your question is to use perforated aluminum with polycarb for the cRio.
Our website is being redone so I can't find any older pics at this time, but in most of the robots we had a rectangle with two side rails (inner and outer, basic 6WD chassis) out of folded sheet metal, with a divider in the middle. In the middle, one half would have a sheet of perforated aluminum on which all of the electrical components would be located, the other half would have the battery, drive motors, and some bot-specific items. We used this basic design from 2006-2008, and something similar but welded in 2005.