Rolf,
From my own experience your comment about using light carbon and using more resin is not right. The type of weave, without a vacuum, has a greater bearing on weight. If you comparing plain weave to double bias then double bias will consume more resin although it would be stronger. Now double bias and a vacuum would be a good combination. I plan on trying this on the outer laminate of another project.
Now if you were talking about light kevlar and carbon or glass you may have a point but only because kevlar is such a bitch to work with.
If the outside was plain weave glass at +-45 would be very easy with very little waste and provide a hull that would most likely have better tortional stiffness and equal in all other respects. The issue is making the overlaps fair. This is easy if painting the hulls but requires more skill if a clear finish. You can work on an approx 0.1mm of thickness of the laminate for 100gm of cloth weight. So if using 200gm you would need a rebate on each overlap (1/5 of a mm) it could be achieved with a thin sanding block and course sand paper.
Just lay the cloth in place on the hull and mark the overlaps and then sand a rebate. If you go a little deeper this can be solved while filling the weave of the glass with clear resin. If painting it is even easier because you can use filler.


BTW:+-45 would work out easier to apply because it can be done in sections and the weave will take the complex shape much better rather than one whole side on the hull in one hit that will not take the complex shape as well.
Regards,
Phill