Hi Nathan,
It is a very frustrating problem! Have you tried a Tilt adjustment flange? Markus Ludes at APM sells them. You will find him very helpful. They make a small (M63 thread) and a large (M82 thread) and it has three screws for tilt adjustment. I have just bought one as I am having tilt issues when I tighten the focus lock screw. I haven't had a chance to use it yet due to the poor weather so I can't say how well it works yet but I would imagine it is just the piece of equipment I need. The good thing is it screws in between the focuser and flattener so the spacing to the camera is unchanged. Here is the link :
http://www.apm-telescopes.net/en/pro...f45bb9e8d2fa41
Hope this helps,
Lucas