Ok, so I've been trying these both out in the flats and off the startup roller (inside out). The closest I've gotten was out in the flats (actually landed, but got excited and then caught my edge). Since then, I haven't been able to land any!!
Inside out it feels like the rope is pulling me off axis everytime and I get worked. I am slowing the boat down to about 19mph, but even then the side of my head takes a beating when trying these. Not sure how to correct this (the getting off axis part). Any pointers/helpful hints appreciated. BTW, I can ride relatively comfy cuffed (both hands) on the side where I'm trying to land the HS BS 1.