Perhaps this is a "No-brainer" but...

Using color vinyl control records makes the markings on my slipmat visible, which can be used to mark cue points (however the drawback is that the "slipmats" move invariably when scratching/pull backs etc, making this method somewhat unreliable).

Why not produce translucent control records with visible markings inside the vinyl itself that the could be used as visual aids to track cue points?

For example divide the control into quadrants and within each quadrant have a series of markers (lines, dashes, hash marks, etc.) visible inside the translucent vinyl. Perhaps each quadrant could use separate distinguishable markers, e.g. one quadrant uses longer lines, another uses shorter dashes, and yet another could use a different marker. Of course, these markings would be visible on both sides of the record.

In conjunction with this the control records label itself could be coordinated to match each quadrant(not sure if this is possible production-wise to ensure appropriate orientation of label/quadrant during the manufacturing process). However all that would be required for the vinyl markings is inserting a layer of tissue containing the marking during the production process.

What do you think?

Of course, another solution would be to make a slipmat with such markings, however, again you would have the issue of changes in the orientation of the slipmat with the vinyl during performance. Not sure what the offerings are in the current marketplace in that regard.

If nothing else, I guess it would be possible to simply mark the records with a permanent marker pen but I am not sure if this would cause performance issues (control record/needle).