Similar to what Alex is doing, I mount both my 70mm and 66mm WO's, using the L Bracket onto one of these, an ADM dovetail adapter plate, this way you can move the guidescope either up or down to establish correct balance.
http://www.admaccessories.com/D_Seri...il_Adapter.htm
I use the 66mm with my Sky 90 and have no problems getting a guidestar, prior to that it was used as the guidescope on my TSA-102 in the field.
Cheers