> I'm wondering whether anyone has ever tried this
It's been tried on model aircraft several times over the years. The main problem is a lack of torsional (twisting) strength... it's quite possible to have a whole wing flutter and shed itself at speed.
> And the French geezer who crossed the channel the first time
> (Bleroit). Pretty sure his was an all moving wing...
Not quite. He had wing warping. The wing root was fixed in relation to the tailplane.