If you have an adjustable bench, you can do reverse hypers over the back of them too. Probably more stable than the Swiss ball, but just as hard to add weight.
All you do is set the bench to a 45 degree angle, stand behind it so it is angling up toward your waist, lean forward down the incline until your hands can grasp the seat in front of your face, and pull your legs up backwards using the top of the inclined bench as your pivot.
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