Isnt there lift above the CU in the form of a pressure wave? Not the big nim towers, just your average summer puff-top? I have had a great time ABOVE the smoke from large stubble fires here in OZ in air being displaced vertically by the rising smoke, surely if viewed like so, thermic cloud will eventually be seen as just a transition point to lighter lift going higher still. Wouldnt this justify the ability to fly through it?
Cloud flying is verboten here, too!

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