advice on final ad lib measure

[Xavier Noria]

I am transcribing the saxophone part of a theme of Dave Brubeck:

    The Dave Brubeck Quartet – Five For Ten Small Fingers

The last "measure" is played ad lib. The way they play suggests eights to me to choose a notation, but they do not look well within the 5/4 tempo (see screenshot).

Which notation would you suggest there? Is there a way to tell Lilypond "from here to the last bar this is free do not automatically add measure bars". Or would you write that in a different way?

    

Screenshot 2014-08-20 21.49.41.png
Description: PNG image