Check out this MCMAP clip of the participants starting their grappling on their knees. I think it's a good idea because it isolates the clinch and ground game, while taking away the footwork factor. The downsides are that it takes away the footwork factor, plus the standing throws and takedowns that are a big part. That's the compromise with all handicap sparring/drills, though.
Mike and I did this in the park at the end of March, though slightly different, but it was a great drill.