Change weight/make invisible individual staff lines.

We can control the number of staff lines, but if we wanted to, say, make the middle line invisible, that would be very useful. In this example I'm trying to make a grand staff that overlaps on a middle c, and the middle c line would be invisible so you would get a single ledger line for middle c.

The only workaround I have found is to use a spacer to move a second staff up so it's only 2sp away from the top staff and make the rests invisible, but the issue is you still get ledger lines that overlap with the lower staff lines which makes it hard to read.