Just me, but because I'm inherently lazy, I would shim the turntable (1 job) rather than attempt to taper the access & roundhouse tracks (multiple jobs) .
I don't have the requested cable,.. BUT (don't ya just hate that?), have you looked into using DCC++, using Arduino products. I'm sure there are several discussions here about it. Just a thought...
Welcome, by the way.
That's good. Back in my surveying days, I was advised you could only do a solar observation two times without a filter. Once with your left eye, and once with your right.