Aj was mentoined by Nat Prog. we have had carbon cross beams and carbon extension tiller for many years and they have been truly tried and tested, breakages nil, zero, zip, nada
And interestly, fitting attached by bolts with holes drilled straight thro' (opposite to AJs thoughts) and still no breakages.
Sometimes the small extra expense pays dividends in the end.

Salpicon de Resplandor
Mk2 1744, LBYC