I worked on this over the weekend, but I have been planning it for a while. I now have both my mounts--Orion Atlas EQ-G and iOptron CEM25P on identical aluminum mounting plates, drilled to match the base plates on my backyard pier and my tripod. I'm using the iOptron Tri-Pier Adapter (8036-TK) for this. It comes with the heavy duty aluminum upper plate (connected to the mount), three posts, and stainless steel hex cap bolts. I drilled the aluminum plate with the same four hole pattern I use on the pier and tripod. I drilled and tapped three holes for the adapter. This thing is solid!