yes there is a very simple way, while with the huge effort to build a carbon one or match another carbon fuselage you may save in the very best case 300 gramms.
But just when you build it with bigger diameter and therefore with more drag, as on the picture before. But there is a way to reduce drag and weight both significantly:
I saved on the Gong foil:
Original fueslage + Stabi
1,05 kg + 0,41 kg = 1,46 kg
0 - convertible fuselage without stabi: 0,33 kg !
So I saved a relevant 1,13 kg !
… which means to reach this, you would have to build your fuselage not out of Carbon, but out of strange matter with negativ gravity
I am sure the Onda will be easy and great for mono, so just try it.
If you want to go light, go mono