At the public range here the standing post area has adjustable ammo trays mounted on the posts. There's a t-handle locking piece on the back of it that you can loosen by hand and shift the tray up the pole and rotate to either side of the pole. I've adjusted one up to the correct height and then dropped a sandbag in it.

I hang onto the rifle like normal but rest my forestock hand on the sandbag. I've done this with my 500NE and it works well.

No photos except for this one showing the posts and trays: