mounting guidescope on top of refractor, Losmandy G11

All,

I want to mount my 5" refractor on my G11, and then mount a guide
scope on top of the refractor. I currently use the side-saddle
system, and I don't like having to balance on two axes. I've spoken
to one vendor who has a solution, but I wanted to ask for input from
anyone who's done this successfully (or not!) Whatever I do needs to
be suitable for long exposure astrophotography.

TIA,

-Dick L.
www.dl-digital.com