Hi, I am buying cord for a ridge line onto which I'll attach a tarp with prusik knots. I believe prusiks work when they are of thinner cord than the cord they are attaching too. So I was thinking to buy 550 paracord (5mm) for the ridgeline and kombat paracord for the prusiks (3mm). Is this a good idea? I have read posts here about using small diameter dyneema etc line for ridgelines, like 3mm, but then do people use 2mm dyneema for the prusiks? That seems very small?