Hi jape,
thanks for your interest. About the choice of materials: Carbon is very light, stiff and yes, also expensive. Problem with carbon laminates is impact resistance. It can crack and break on hitting a rock during a fall or so. Kevlar fibre is a synthetic polymer material, well known for impact strength (its being used in bullet proofed stuff). What I expect from this combination - and I am no expert in this and didn't do a lot of research too - is: On impact, the panel, mainly the carbon and the resin, might break but the Kevlar fibers are supposed to hold things together so the panel will not totally fall apart. I do not worry too much on flammability. The original panel is made of ABS, a thermoplastic material with much lower melting temperatures and higher risk to burn, than the resin, which is a thermoset polymer, doesn't melt. However, I'll stick some heat-shield material on the inside of the panel in the areas close to heat.
Of course I consider to do more, after developing some more skill and know-how. The tank is also bloody wide, when you ride up steeper trails, standing up, its "John Wayne-style" again. Much is possible, also on re-designing cockpit and so. But, time...
Cheers,
AW.