Dear pianists, please help me notate a left hand maneuver

Hi there pianists,

I'm making a copy of an SATB-and-piano score, but I am not much of a piano expert and I could use a hand with finding a good way of notating which notes are in the left and right hand.

The first image shows how the original score wrote the hand maneuver. As you can probably see, the pianist is meant to play the bass clef notes, holding the sustain pedal, and then split the treble clef chord between their left hand and right hand, with the bracket to the right of the note indicating which hand plays which notes. It's important for them to know which notes are in which hand because of the arpeggios moving in opposite directions for the two hands.

The second image is my current best attempt at replicating this in Musescore, and it doesn't work nearly as well. While I do think the addition of the line helps to show what the pianist is meant to do, without having the brackets to make it clear which notes are in which hand, the up and down arpeggios are much less clear. If the notes weren't semibreves I could use up stems and down stems to show which hand is which, but no such luck here (unless I rewrite the note to be two tied minims, which seems like it would create more questions than it answers). Musescore has a bracket symbol similar to the one used in the original score, but (a) that symbol remains firmly attached to the left-hand side of the notes no matter how much I drag it around and (b) the symbol is supposed to mean "do not arpeggio these notes", which contradicts the arpeggio and would therefore lead to a lot of confusion if it was left there.

I'm willing to change just about anything about how this is written so long as it plays the same: accuracy to the original score matters a lot, but I don't have to replicate the original symbolism so long as the intention is clear. What symbols would you use to make it clear how the pianist should play this section?