people fly capiche's at my club in the UK with the CG way back - like 55% back.

Hands off and inverted they apparently climb - wing loading I guestimate at about 15oz.

I think a lot of people thought you had your CG behind your NP.

Even paper planes set up like that tend to tumble!

One thing I would like to mention though is that if the plane's CG is behind the NP and the thrust force is greater than the weight of the airframe, then the wing isn't doing much, so perhaps CG doesn't matter then - it's effectively a helicopter

Is that what you are saying Dick? or are you making the point that perhaps birds or insects operate in a weird laminar flow low Re regime where the conventional rules do not apply?