110 retro fit rear shoulder belts

I am working on an early rest of the world defender and am trying to retrofit rear shoulder belts for kiddie safety... I had planned to build in a roll cage style hoop behind the 2nd row of seats but it's getting more and more complicated to position without destroying the load space.
Has anyone achieved this by strengthening the side panel and attaching the shuolder belt in a normal position?
I'd really appreciate anyone's experience or ideas
Thanks
RTC

You can use the hard top type shoulder mounts 395586 & 7. LR have a kit (RTC6065) for the inner floor mounts and the outer mount lower is #347844.
There are alternate upper mounts MXC3282 & 3, dunno if they are still available.
Gord'n

I'm working on correcting a ROW install now with factory parts. I'll post pictures in a week or so.

Looking forward to how it works out, VTRover.