I like really wide double-side velcro. With the soft side inside it does not bruise but you can double the spare length over for a tail for quick-release.

If you are worried about bruises - put the subs wrists into sweat-socks for padding or use athletic pre-wrap tape.

I've never used Bondage Tape but it is available. (I actually spotted a roll under my daughters bed but cannot bring myself to ask her about it.)

I have always wondered if you could take a old pair of the subs tennis shoes and screw them to a board to create a leg spreader. Not as sexy as cuffs, but secure (and you reduce the risk of stubbing the subs toe.)