I have various imaging optics and all suffered from the same thing, it was a pain to change from one setup to the other. I have lashed out and bought the side by side bar etc from StarStuff
Here
http://www.starstuff.com.au/index.html
What this all means now everything is a 'module' and can be easily swapped and added as need be. Here is some images of the 300mm Canon lens imaging setup.
The black lens is a 16 to 180mm F1.8 zoom and I can just see the Helix nebula in real time through it with the Gstar on the computer screen. Obviously most other nebs are easier than this. The 100ED in this configuration is the guidescope.
What is even better the center of gravity is closer to the RA axis so there are less weights on the counterbalance shaft. Dynamic balance can now be far more easily obtained. Whats even better it is far easier now with or without the fridge to get very good dynamic balance.
I will show the other combinations when the weather cools down. When it is 38C it is not good for me or the optics to be outside.
The whole assembly is far solider than the 100ED mounted on top of the 150mm achro and uses far less counterweights. when in this mode.
Bert