Adapter plate for EQ3, where?

Want to mount an ST80 to an EQ3/Astroview mount. However, the spacing of the holes in the mount are farther apart than the ST80 tube is long. I know the mount is designed to have the tube rings directly couple to the mount rather than using a saddle plate/dovetail, but I don't see how this will happen given the situation. Orion used to sell Adapter plates for these mounts that had a 1/4-20 screw to allow mounting a camera, but these are no longer on their website (this would work as the ST80 has a mounting block).

Any ideas on where to get an adaptor plate, or other suggestions; or am I going to have to get out my tools and rig something?

Thanks
John