I agree, it is a balance issue. Increasing rake could help but, if you don't have a lee helm in stronger winds, you might end up giving yourself more weather helm than you want.
Do you pull your main boom to center, in light air, while sailing upwind? You are a fractional rig.
If you tighten the backstay, you will also tighten the forestay which could help flatten the foresail and depower it in light winds. Of course, that also flattens your main. Bring the boom to center and give it a try. I would put some rake into that rig also.
-Will (Dragonfly)
