Get one of those reacher-grabber things they promot to the elderly; that'll let you access more of the space (you can use the grabber as a pusher as well).

Then store lightweight things that you'd like somewhat accessible and are aggravating to store somewhere else. If this was my mom's space (she loves to travel), she'd store her empty luggage in there. If this was my sister's, she'd put all her holiday stuff into plastic bins with large handles and store that in there.