E-AB equals Options
There are a lot of options when it comes to our E-AB (Experimental - Amateur Built) aircraft.
Stein builds custom panels for a living and probably has the best handle on what others have done to provide redundancy in their panels.
My personal favorite is the
Dynon D1 and D2 Pocket Panels. The Pocket Panels have an internal battery and are not tied into your pitot static system, thus, if either become blocked, they will not impact them and in the event of an alternator failure, they will continue to run for a few hours.
For backup nav, get a WAAS enabled handheld and an
AirGizmos Panel Dock to mount it.
The communicate part of the equation would be nice but as you know, there are procedures to handle radio failures. Still, you could mount one of
Sporty's SP-400 Handheld NAV/COM's in your panel and wire it to a separate antenna and put a pair of headset plugs on the panel just for it.
With those three items installed, you can keep your plane upright, navigate, do an ILS, and communicate during a full electrical failure. At least, in theory. I've never flown with the SP-400, so I don't know how well it works and the handheld COM radios I have used in flight without an external antenna are about useless. A better radio than those I have tried might work better.