Key working assumption:  Light as possible, no IFR needed.  So light VFR instrumentation

Ah forget that....what about a Grand Rapids Technology Twin EFIS & EIS??......gorgeous.

Anyway its my first idea, and I was experimenting with epanel builder.

29/09/2007 - I have seen a great combined EFIS, GPS & systems monitors.
My second try is to make use of MGL Avionics Stratomaster Enigma.  Two of them linked to one another via USB; standby compass, airspeed indicator and altimeter.  Garmin radio, transponder and audio panel.  I like the programmability of the Enigmas, and with two of them I can always have a full screen moving map running.  They are great value for money too.