Interesting idea, although I suspect a truely electrical tourer is a while away.
On the hybrid idea, whilst an electric motor maybe 90% efficient, a small APU is not going to get any where near 20% efficient, so you would still be better off with a good old fashioned donk. If want rid of the nasty bits of a piston engine, forget the batteries, put a small APU in the aircraft, wire it up to an electric motor bolted to the prop and off you go. It won't be quiet, but you get around most of the problems with the old Lycoming. Plus you would have all the electrical power in the world for all the modern fancy nav kit. Mind you I wouldn't like to buy or maintain the APU, nor would I like to share a small airframe with one. 60,000rpm spinning just behind/infront of you? no thanks.