well then you would need some extra bits to hold the spur, belt tensioner and motor clamp, as well as some thing to stop the diffs from falling out that would also need to hold the shocktowers up.
Why bother ?? there are plenty of cars that already come with plate chassis. Plate chassis were what was used before designers had the freedom to design molded chassis without losing rigidity, so to me, a molded chassis looks better. more advanced.
Not that there is anything wrong with plate chassis !!! And carbon fibre does look pretty cool, just not as much after you've had about 10 cars that have them.