Have not seen the particular video but I think I'm understanding what you want to do.
I have thought about doing something similar with a "UCR" rather than a whoopie. The UCRs do not require as much line but don't constrict as well. For a tarp line that is not supporting your body weight the lack of constriction might not make a difference.
Prusiks are just so much quicker and can be added/removed easily. I've never bothered with anything more fancy.