I've got this lengthy solo passage in my piano piece (a transcription of a symphony, where this is the solo). The right hand plays the solo, and the left hand provides the quietest possible background harmonics, in the form of a constant, near-silent F-minor chord tremolo (soft strings in the original). Question is, because the solo is in an overlong bar (which takes about forty seconds to play), how do I notate the tremolo.
So the latter is my preferred solution, at this moment. The question is: is there a better, more 'legitimate' way, to notate a tremolo of indeterminate length?
EDIT: Sadly, it looks like the trill notation as suggested by Laurence Payne is causing irresolvable issues with the music notation software I use. I would love to hear if that is the only suitable notation or if there are any alternatives. Leaving a bounty for that purpose!