Tremolo Between Hands in Piano Music

Can someone help me figure out how to place a tremolo between two staves in piano music? This tremolo is executed between the hands, and I can't get the tremolo sign to appear when both sets of notes aren't written on the same staff. I also can't get the tremolo to be short enough that it doesn't overlap the second chord.

This happens quite regularly in piano music, so I'm sure there's a way to do it.

(In the screenshot, the second chord needs to be written on the top staff. The arpeggio bar is a placeholder for a random key cluster right now, which I also can't figure out how to notate.)