It is tough enough towing a sled... adding the extra weight of a "rider" (200 lbs or more) is crazy. We use bumper to ski loops of towed sled, no rider and remove drive belt. Sled tracks great at any speed, just allow room to slow down when you have to stop if you're towing fast.
Haven't used the tow rope in a while, last sled I towed was a AC ZR 500 two years ago (primary clutch broke apart into a few pieces).