RX8 Rear Sub Frame

I'm using the entire rear sub frame and differential from a Mazda RX8 and have just finished fabricating some simple brackets to bolt it to my space frame.  The sub frame has 6 massive bolts that have a U shaped alignment pattern so figuring out how to get everything squared up was interesting.

Here are the 6 bolt holes finally completed (obviously the car is upside down in these photos):

Sub frame attached:

I'm using 16 gauge tubing nearly everywhere... This is fine in most cases but it can easily crush under a bolt of this size, so I've welded some 1/8" stock around the tube for extra strength at the main bolts locations:

 Before:

After: