The instrument panel above is my current thinking on what I need. It looks pretty sparse because the Dynon EFIS takes the place of so many other instruments. I don't have dual COM in the panel because I'm planning on having a handheld COM as a backup and for the time being I'm going to use a handheld/portable GPS unit. GPS is still on the way down in price and on the way up in functionality. It will be at least a year before I'm finished and have flown off my 40 hours. So, I'll re-evaluate GPS at that time. 

I'm considering using one of the copper tubes that run to the heater up front as an electrical ground. The method of connecting the copper tube to the electrical system is important. #1 it has to be reliable; #2 has to stand up to vibration and heating/cooling cycles; #3 see #1!
The diagram above illustrates a connection that will meet all those criteria. The copper saddle around the tube will be soldered - but it will also have a machine screw through it that will connect to the Instrument Panel ground strip. If the solder should ever come undone (very unlikely) the machine screw will still hold things in place.