It's all technique. I own a Dart 18 and can right it without problem, though the time to right is directly functional to the amount of booze I consume. Still, it's never taken more than 5 minutes. No righting line, bag, or any other contraption is necessary.

1. Uncleat the main. Unclean the jib.
2. Detach jib sheet and throw it over the hull in the air between the forward beam and the side stay.
3. Stand on the bow until they're pointed directly into the wind.
4. Grab the jib sheet and lean back. The key is to use your leverage and get LOW. As in, almost to the water low.

Oh, and I'm all of 5'10" and a whopping 165lbs.