Where to attach 3/4 points setbelts?
 

I need race seatbelts for my downhill rides on mount Hakina.:lol:
Where to attach the rear points without a roll bar? The Isofix on the shelf seems too weak, and the stock rear belts mounts are way too angled (more than 45 degrees).
Harness bas is not to be considered.

Suggestions needed, please!

The closest you can get to using a 4-point safely without any additional parts is the Schroth Rallye 3 ASM which mounts to the C-pillar (shoulder part of the stock seat belt in the rear seat). However, the safety of this belt is still highly debated and I still don't know if I'd use it outside of an autocross scenario.