That was pretty cool! Nice ingenuity.
Have you ever done those with just your heels up on a big swiss ball? Just go up in a bridge pulling your heels in to your butt until the soles of your feet are on the ball? You can't add resistance, but it works. Not sure if your angle being so much lower might not be better though.
I am Anton Zdravko Martin!
Best meet lifts: Sq 150 Kg (330 lb), Bench 120 Kg (264), DL 160 (352) @89 Kg (197)
Best gym lifts: Sq 375, Bench 280 (pause), DL 385 @205 or less
Goals beyond my wildest dreams, 600 Kg raw total, 200/160/240
Hack away at anything which isn't essential. Do what you love, and do it often. Fazc.
Everything competes for recovery so more assistance is not always the best idea. miked96