The Meade 3.3 comes with a SCT to T- thread adapter and two T-thread extensions. Remove the T-thread to 1.25" adapter from the Infinity and you will be using the adapters that came with the Meade FR. Attach your FR to scope and then the SCT to T-thread adapter to the FR and the longer of the two extensions and then screw this into the Infinity. This will give you a reduced focal reduction but improve the image and reduce the coma and vignetting.
I like this idea, but then you can't use 1.25 or 2 inch filters right?
Correct. That is why I prefer to use a T-to-2" nosepiece that you can insert into your normal visual back. You can then put a 2" filter on the end of it if needed. Another option is a more convoluted combination of adapters:
= camera + T-thread spacer (as req'd) + T-to-2" adapter + 2" filter + 2"-to-SCT adapter + Meade FR
An advantage of going with all threaded connections instead of thumbscrews is you get better alignment of the camera with the telescope axis. Your click-lock visual back is giving you this same advantage of good alignment. I purchased all the req'd adapters from AgenaAstro.com.
Ok, how about this
= camera + T-thread spacer (as req'd) + T-to-2" adapter + 2" filter + 2"-Baader click-lock + Meade FR
With all this in the optical chain, determining the spacer will be the key