The one I've rented is a walk behind with no blade so I 'employ' my wife to rake the crumbs back it. They have a Ditch Witch as well but I've never rented it.Flip, when you rent a machine why do you have to backfill with a shovel... "backfill is easy with a shovel"? If you're going to rent a piece of equipment to get something done, why just do half of the job?
Even my old machine will do that. Has a 6 way backfill blade!
Maybe next time I will and try it out. They even deliver for me. We have mostly blow sand soil here so the crumbs are usually light.
Even the walk behind will trench almost as fast as I can walk.