I'll see if i can find the pictures of the mount i made. Its the same idea as the stock support, but more rigid and smaller. the problem is with the 3" pipe there really isnt much room and you're likely to hit.
As for the flanges, I have to grind the side of the left flange about 1/4" in (looking at them). imagine them side by side, but the left one wanted to overlap the right one a bit. When I get home from work later today I'll dig up some pictures from the build-it'll explain better.