The required instruments for VFR flight are listed in 91.205 for standard category airworthiness certificates. This specifically does not apply to E-AB aircraft, by definition. However, it would be foolish to fly with less than that list, and in my Operating Limitations it says to fly for night flight or IFR flight, I need the things listed in 91.205(c) and 91.205(d), both of which refer to 91.205(b) as a predecessor requirement. The "six-pack" is not actually required for VFR flight. So, if we eliminate engine instruments from that "TOMATO FLAMES" list, you're left with an airspeed indicator, an altimeter, and a magnetic compass. So, a bare G5 unit will do the first two. If you add the GMU 11 ($275), then you get the magnetic compass too.