So you can remove the perch and retain the circlip on the shock?
If so, then that's pretty easy because the ground control or perhaps most sleeve simply sit on the circlip with a machined lip that covers the circlip. In effect, circlip failure is almost eliminated.

Yeah ground control uses eibach universal 2.5" inner diameter coilover springs.

I'm glad that there is some discussion going on, what has helped me could help others too