Use a hard‑backing plate and a small counterweight on the opposite side of the rail. Slide the whole scope on a dovetail, lock it with a quick‑release clamp, and line it up on a bubble level. Then run a dial indicator across the mount so you can see the drift in real time. Adjust the counterweight until the indicator stays in zero as you rotate the scope. That way the pivot holds and the drift is counteracted without any fancy electronics.