If you are VFR only, a single screen EFIS w/ backup battery and a charged GPS-equipped iPad in your flight bag is all the backup you should need. You're double-redundant at that point. When you are VFR, most of your flight instruments are just backups for what you see outside all of all the glorious glass in a Kitfox.

If you absolutely, positively can't be without a round backup gauge, install an airspeed indicator. Trent's setup with an ASI behind his iPad is pretty clever. Unnecessary, in my opinion, but clever.