I keep looking at the pic. and i'm confused
It looks like there is a bar that runs to the lower shock mount on the swinger .
If it is , then i would think that there are no mounts to connect it to the sub frame . You just slide the tubes over the sub-frame and bolt it to swingarm . It has to be this way (free float on the subframe) , because the swingarm needs to pivot and if you bolted the 12 bar to the subframe it would make it completely solid .
Also , since the tubes are around the subframe , stress will be applied evenly . And the third bar running to the swingarm would take some of the stress off the subframe , too .
I could be way off , and the pic. might be confusing me , but that's what i see
And i like the idea .
The rollers seem very cool for a few tricks but that's gonna really hurt when you pinch yourself .