Make it possible to increase the mouse area of splitview handles without increasing the visible size of the handles

I want to set the SplitView handle to be a 1px line, but this means the draggable area is so small it's practically unusable. I think the draggable area should be equal to the width (assuming horizontal orientation) plus an extra few pixels. This width could be defined as a property, or let the style define it. Something like this:

import QtQuick
import QtQuick.Controls
SplitView {
    dragHandleExtraWidth: 5 // default value 0
    handle: Rectangle {
        implicitWidth: 1
        color: "black"
    }
    Rectangle {
        color: "red"
    }
    Rectangle {
        fillWidth: true
        color: "green"
    }
    Rectangle {
        color: "blue"
    }
}

which would let the user click and drag from up to 5 pixels away from the separators.

It would probably be better to make this extra area draggable after the user has hovered over the handle itself (i.e. replicate the behaviour that is used in Dolphin's draggable areas). This means they can still click on the areas surrounding the handle.