hitch mounting question

[feelstranger]

Hello all,
I'm about to mount a hitch to my avant.  I can't quite picture what the bolts are doing from the instructions with the hitch.
I was wondering if anyone with a mounted hitch could take a picture of the inside trunk area that shows how the bolts are in there?
Do they end up on the little lip on either side of the frame rail inside the trunk?  
And the other U bolt unit must end up with nuts inside the frame rail itself?
I'd just like a clearer picture before I start drilling!
Any help appreciated 
Thanks