OK I just mocked up everything... not sure how I like using the extended bases, for the front its necessary but for the back it placing the ring to far forward. Can I not use that cross bar piece and slide the rear mount back on the base? Think I might try again and see if the local stores have the standard rear mount before I secure everything. Also, the screw in the front mount wont go in all the way, the hole is too shallow so I'll have to grind down the screw I guess.