By SLP, what type of bed do you have? Does it have wooden slats at the bottom etc? We use Japanese silk rope for arms during most of our sessions and use a spreader bar attached to a rope at the bottom of the bed for leg restraints.
Probably best for you to look at something similar to this
https://www.lovehoney.co.uk/product.cfm?p=31705
Rather than getting one under bed restraint, we found that getting the ones which have four separate ties and cuffs work better for most beds, unless you have a divan! Haha. We even bought some cheap picture hooks once and screwed them into the bed to give us the ability to tie anything to them.