In Lilypond one can make long full-measure rests with:

<pre>
    \compressFullBarRests
    R1*12
</pre>

which outputs:

![enter image description here][1]


  [1]: https://i.sstatic.net/ZBlDD.png

Is there an engraver I can turn off, or some other way to remove the number from above the rest (for a multi-measure rest of arbitrary length)?

Also, is this the preferred way to engrave this or is there some other better way to specify arbitrary length rests?

To clarify, this is for a section in which another instrument has an improvised solo of arbitrary length.